Chapter 1: The Locked Room Trick Game

The assassin sat by the window, looking through the scope of their rifle. The target's face appeared in the view of the magnification lens. The killer took a breath and waited for their heartbeat to steady. The first time they'd killed someone, their fingertips had trembled with fear, and the second time, their heart ached with guilt. Those feelings were a distant memory now, after they'd gone on to kill dozens more people, but the remnants of those emotions still lingered enough to make their hands shake. So they emptied their mind as much as possible and waited for the feeling of peace, so like when you poured yourself a cup of coffee first thing in the morning. It was the only way they could do the job perfectly.

The moment their emotions had grown calm as the surface of still water, they pulled the trigger. The shot hit the target square in the head, killing them.

The assassin took a deep breath. Setting down their rifle, they took a cigarette from their pocket and lit it with a lighter. Just as they inhaled the purple smoke into their lungs, their cell phone rang. The caller was an agent who brokered contract killings.

“Hey, how are you?” the agent said when they answered the phone. With no further preamble, he immediately said “There's a job I need done right away.”

The assassin chuckled. This man was always like that. He had no concept of small talk. However, the assassin didn't like small talk, so they enjoyed the man's stance on the matter.

“A job? Ah, that's fine,” the assassin replied. The agent told them “Thanks, you're being a huge help.” and then added a somewhat cryptic follow-up:

“By the way, the client did give me one particular condition.”

The assassin frowned. Ah, so this was a troublesome case. Realizing what they'd gotten themself into, their reply was reluctant.

“What is the condition?”

“They want you to kill all the targets in locked rooms.”

A bitter smile formed on their lips. Ah, so that was it... It was certainly a troublesome condition.

After the world had been flooded in locked rooms, a new industry was born: Hitmen who specialized in locked room murders. They were called “locked room agents”, and when they killed their target, they always left them in a locked room. Come rain or shine or sleet or hail, nothing would stop them from delivering their victims to grisly ends in locked rooms.

And the assassin was one of those locked room agents. That's “was” in the past tense, though.

So the assassin replied with a sigh.

“I've already retired from being an agent. Now I'm just your normal, everyday assassin.”

From the other end of the phone, there came a voice of genuine amusement.

“What, you're saying that now? You, the one who used to call yourself the 'Living Locked Room Library'?”

That was a name they hadn't heard in a long time. One who knew every locked room trick in the world and could use them to their advantage – that's why they'd been dubbed the Living Locked Room Library. People had started calling them that, and eventually, they'd started calling themself that. Even though it had only been a few years ago, it felt like another life. They'd been much younger then... They'd been that sort of assassin... the Living Locked Room Library remembered.

As they were standing immersed in those old emotions, the agent starting pleading.

“Come on, do me a solid? We're old buddies, right?”

Indeed, they had known him since they'd started work as a locked room agent. However, the career of locked room agent had only existed for three years, so it wasn't like they'd known each other that long.

But the Living Locked Room Library had already made up their mind to accept the job. There was nothing left to it. It had been a long time since they'd received a request for a locked room murder, and they were getting excited. They hated themself for being so easily manipulated. In the end, they couldn't escape the siren song of a locked room.

“Okay. I'll take the job.”

When the Living Locked Room Library said that, the agent let out a happy noise. Then, as if to cover up his embarrassment, he very formally announced “Thank you for your assistance.” The Living Locked Room Library didn't mind that side of him. He was a good, honest man at heart, so much so that it was frankly absurd that he was involved in the criminal underworld.

The Living Locked Room Library asked the honest man a question.

“So, who are the targets?”

“Ah, um...” They heard the sound of papers ruffling on the other end of the line. “There are quite a few targets. I'll send you a list later. But, one of them is pretty big.”

“Who is it?”

“Do you know the name Aoi Otomigawara?”

The Living Locked Room Library nodded. Of course they did. That was how they could respond like this.

“That's one of the richest people in Japan.”

If they remembered correctly, she had assets approaching one trillion yen, if you included stocks and real estate.

“This job has multiple targets – including the tycoon, Aoi Otomigawara,” the agent said. “Otomigawara lives on a private island she owns by the name of Wire Mesh Island. It's a lone island in the Pacific Ocean.”

The Living Locked Room Library wore a dissonant smile.

“It's a perfect stage. Like something out of a mystery novel,” they said. “So, the curtain will rise on a series of locked room murders on a solitary island in the distant sea...”

The cherry trees in the schoolyard were already flowering, and for the first time, I truly realized it was already mid-April. Two weeks had passed since the start of the new semester. I, third year high school student Kasumi Kuzushiro, was staring blankly at the view outside the window. I was still leading the same life as ever, reading mystery novels and neglecting my studies. I felt like my brain was being slowly suffocated with a huge ball of cotton. I'm sure I won't realize the true gravity of the situation until I've already choked on it. Sorry, future Kasumi. I hope you can live a happy life.

I pushed myself up, then made my way down the sunlit hallway of the new school building. There, at the end of the hall, slightly shaded, was the door to the literature club.

On the other side of the door, a beautiful girl with long black hair flipped through a paperback book. She was a stunning beauty, and she wore a serious expression as she narrowed her almond eyes at the pages. I was curious what she was reading. She must have realized, because when I approached, she noticed me and held up the cover so I could see. The title was “Mystery of the White Chalk Castle”.

“I impulse bought it at the bookstore yesterday.”

So said Shitsuri Mitsumura. Mitsumura had gone to the same school as me in middle school, and we were old friends who'd been part of the same literature club. And since she'd transferred to this high school last January, we now went to the same school again. Afterwords, she'd become a member of the literature club, and our old routine of spending time in the club room after school had resumed as though nothing had ever happened. Mitsumura and I were the only two members of the literature club. We'd meet up in this room after school, reading books and playing board games to our heart's content, and our advisor would scold us for not doing enough club activities.

I was sure that day, too, would be a pleasant day of leisurely not doing club activities.

I looked at the cover of The Mystery of White Chalk Castle that she showed me. It was a book I didn't know. Intriguing.

“Is that a mystery novel?”

“No, it's pure literature.”

“Even though it says 'Mystery of'?”

“I know, right? What a surprise. I was completely fooled,” Mitsumura said, raising her eyebrows. “Even though it's called 'Mystery of' something, it isn't a mystery at all. The title is a complete fraud. Should I sent the publisher a strongly worded email?”

After pouting for a moment, she spoke with a hint of frustration.

“Well, it's entertaining enough that I suppose I can forgive it.”

With that, Mitsumura lowered her gaze back to the paperback. Apparently, she was in a literary mood today. I had actually been planning to invite her to play a board game today, but the atmosphere didn't feel quite right. I felt like if I said 'I want to play a board game', Mitsumura would smile at me and say 'I see, so Kuzushiro likes to play board games' in an aggravating voice. My pride wouldn't allow that.

With no other options, I reached for the club room's bookshelf to find something to read.

There, I found something nostalgic. I pulled it out and held it in my hand. It was a collection of texts. However, they weren't bound, but were a simple stack of B5 copy paper held together by staples.

That's why it was so nostalgic.

It was a collection of writings that Mitsumura and I had made in middle school. There were six short stories, three each by me and Mitsumura.

The reason why this collection of works I'd made in middle school was on the shelf of my high school's literature club room was because shortly after I'd joined the literature club, I'd brought it to the club room and placed it on the shelf. I'd called it a prank, but even though I was the one who'd done it, I didn't really know why. My motive was unknown. I think I might have wanted someone to find the collection and ask “Who brought this?” Or maybe I just wanted someone to talk about my works. I wanted to hear people talking about the girl who'd made them with me.

However, none of the upperclassmen in the literature club ever noticed our stories were there, right up to the day they graduated.

I opened the collection in my hand.

At the beginning was a short mystery story written by Mitsumura. The opening line was “A locked room is romance, art, and fantasy all in one.” I couldn't help but chuckle. That was so like her.

“Isn't a locked room just fantasy?”

I murmured that to myself.

But I couldn't say that anymore. The world had changed since that murder in the winter of three years ago.

I took out my smartphone and checked that day's news. An article caught my eye, and I sighed.

As I'd expected... I knew I would see one.

My smartphone displayed a news article about a locked room murder that had occurred in an apartment in Tokyo that morning. It was exactly the 60^th locked room murder case that year.

I had been three months and two weeks since the start of the year, and in that time, 60 locked room murders had been committed.

I thought to myself that it was a bit more than usual.

When I got home after club, I found an envelope in the mail box. The envelope was made of a high quality paper, and I briefly thought it was a wedding invitation, but it wasn't addressed to my parents, but to me, Kasumi Kuzushiro. When I turned it over, I saw the sender's name was written as “Aoi Otomigawara.”

Of course, I knew the name Aoi Otomigawara. She was one of the richest people in Japan. She was the president of Otomigawara Industries, which manufactured everything from stationery to electrical appliances, and their latest product, an adhesive that dissolved in hot water, was impressive. It was strong enough to hold objects weighing tens of kilograms in place, but just pouring hot water on it would cause it to melt and easily be washed off. It was selling well, said to be useful for things like model making.

Otomigawara was still young, if I recalled, only in her mid-twenties. Of course, she hadn't founded the company; she'd inherited it from her parents, but according to the media, she was talented in her own right.

But what did this business tycoon need from me? I didn't know how she knew my name, let alone why she'd bothered to look up my address and send me a letter.

I took the letter inside and cut the seal with a pair of scissors. When I inspected its contents, my eyes automatically went wide. I'd had no idea what the letter possibly could have contained, but what I saw went beyond my wildest imagination.

It was an invitation. Moreover, it was an invitation to a mystery solving game.

“You are invited to the Locked Room Trick Game” – That was how the letter began, printed in an extravagant font. I read it over and over again, confused.

Finally, I began to understand.

It seemed that Otomigawara was planning to invite famous detectives to her private island, Wire Mesh Island, to play a mystery solving game called the “Locked Room Trick Game”. And the prize was one billion yen. That was enough money to do whatever you wanted for the rest of your life.

The question was, why was I invited to such a high-stakes game?

That had also been clearly written. As it happened, I'd visited a certain mansion in Saitama last December and gotten involved in a series of locked room murders that took place there. The letter read “We would like to invite Mr. Kuzushiro to participate in the game in recognition of your brilliant success in solving the serial locked room murder case.” No matter how many times I read it, the words remained the same, and in a way, that was what confused me the most.

Because I had done almost nothing in that incident. The one who'd solved the case was the beautiful black-haired girl from the literature club – Shitsuri Mitsumura. I had tried to solve the mystery myself, but in the end I'd done nothing but haplessly follow her lead. Since it said here that I'd brilliantly solved the case, I could only assume that some rumors had started spreading and the information that reached our host was extremely inaccurate.

In other words, I shouldn't have been invited to this game.

However, that one billion yen prize money was extremely attractive. The invitation said that the game would be held during Golden Week next month, so even I, a student, could participate. And even setting aside the prize money, I had a personal reason to want to visit Wire Mesh Island, where the game was being held. Because as it happened, that island was famous among mystery fans.

So I definitely wanted to go to Wire Mesh Island. What should I do? Should I just accept the invitation? As I was worrying about things like that, the intercom rang. My mother was away at work, and I didn't feel like dealing with it, so I tried ignoring it, but it kept ringing over and over. Our visitor had very bad manners. When I reluctantly opened the door, I saw my childhood friend, Yozuki Asahina.

Yozuki was a fairly well-developed beauty with fluffy brown hair, a decently proportioned face, and a fluffy head. She looked loose and fluffy, and her head was loose and fluffy. Her birthday was the other day, so she was now 21 years old.

With a confident attitude, Yozuki immediately started talking.

“Kasumi, I think I'm going to go look for the chupacabra.”

Oh. So she'd finally lost it.

“...The chupacabra.”

“You don't know? It's a type of UMA (Unidentified Mysterious Animal). It has big eyes and attacks sheep and... You know, the alien.”

No, I'm pretty sure the chupacabra wasn't an alien. More importantly, the question was why she was looking for the chupacabra.

“You know, I really like UMA. I've been reading the occult magazine 'Mu' for as long as I can remember.”

I had a terrible sense of deja vu. This was exactly the same silliness she'd said before when she went looking for a yeti.

I swallowed a sigh.

“Well, good luck with that,” I told her, forcing sincerity into my voice. “I'm sure it'll be tough to find the chupacabra, but I hope you make it back safely.”

Please don't let this be our last conversation. I couldn't bear the thought of losing my childhood friend to a chupacabra hunt.

Seeing me looking so depressed, Yozuki let out an exasperated sigh.

“What are you talking about, Kasumi? You're coming with me.”

I wondered what in the world she was talking about.

“...Are you asking me to accompany you to South America?”

Look, she's my friend, but there are still limits to what I'd do for her. Seeing the look of astonishment on my face, Yozuki explained.

“What are you talking about, Kasumi? We're only going to Kanagawa.”

Okay, now she'd lost it.

I rubbed my eyes. Her confident face remained in place. Looked like she was serious. I hoped there was some sort of mistake.

I asked her straight.

“So, why are you going to Kanagawa to look for a chupacabra?”

“Well, obviously, because there's a chupacabra there.”

She said it as though I'd asked something obvious like “Are there mountains there?”

“...There's no way there's a chupacabra in Kanagawa.”

“Yes there is. Because there's the Kanagawa Chupacabra.”

“The Kanagawa Chupacabra.”

It sounded more like the Tokyo Ghoul sequel we never got.

“In the past, all the continents of the world were one – the supercontinent, Pangea,” Yozuki explained, sounding proud of herself. “That's why it could walk from South America to Japan.”

“So the chupacabra came from South America to Japan during the time of Pangea?”

“Yeah, it's possible.”

It really wasn't.

Pangea existed hundreds of millions of years ago, so it was doubtful whether the Japanese archipelago even existed at the time.

Anyway, I'd already made up my mind to turn her down – I was seriously not in the mood for this. As I prepared to tell her so, I unconsciously glanced down at the invitation in my hand. Yozuki noticed and quickly showed interest.

“Hey, Kasumi, what's that?”

Quick as a seasoned pickpocket, she snatched it out of my hand. She looked at it, and her face turned shocked.

“Wire Mesh Island...”

Yozuki's eyes were wide as saucers as she read the name of the island off the invitation. I was a bit surprised by her reaction, so I tiled my head to the side and asked:

“Do you know about Wire Mesh Island?”

“No, not a thing,” Yozuki said. “But it's the same place I want to go. Because Wire Mesh Island is where the Kanagawa Chupacabra lives.”

A month later, I was leaning on a ship's railing, staring blankly at the clear Golden Week sea. The sea breeze felt good. Like a cat lying in a sunbeam, I let out a soft yawn as I watched the waves left in the ship's wake fall back into the sea.

That morning, Yozuki and I had headed to the port at the time and date written on the invitation, boarding a ship that, as promised, had come to take us to Wire Mesh Island. I had informed them in advance that Yozuki would be coming with me, so we were both able to board without any difficulty. It was a large cruiser, able to carry about 20 people, but we were the only passengers. When I asked the captain about it, he told me that all the game's other participants had gone to Wire Mesh Island the day before. As students with inflexible holiday schedules, we were the only ones to arrive a day late.

“We'll probably land in about an hour.”

That's what the captain told us as we left port. It seemed he was an employee of a shipping company run by Otomigawara, in charge of picking up and dropping off guests to the island.

As I thought about things like that while leaning on the ship's railing, the cabin door opened and Yozuki arrived on deck. Her eyes were red and swollen with tears. I was surprised to see her like that, but I quickly realized why. A while ago, I'd seen Yozuki watching a movie on her tablet. It was an Italian short film with a reputation for being a tearjerker. It must have lived up to the hype. I'd seen it before, and it was definitely a good movie. So I understood how she felt. I was just about to say some words of sympathy when Yozuki said “No, that's not it.”

After rubbing her swollen eyes, Yozuki showed me the screen of her tablet. In the upper right corner of the screen was the out of range symbol.

“Can you believe this? It's too much.” Yozuki sniffed. “I was at such a great part when the video suddenly froze.”

I took out my smartphone and checked the screen. Indeed, I was also out of range. But it wasn't that surprising. We were already far from land.

“Ugh, this is the worst. I really want to know what happens next...” Yozuki lamented. “It was such a good scene.”

“How far had you gotten?” I asked. Mostly I just wanted to brag about having gotten to see it before her. Yozuki said “Um, that scene,” with an air of regret.

“The part where the main character snipes the enemy who'd holed up in the building.”

Ah, that scene. In the scene, the main character, whose girlfriend had been taken hostage, managed to land a difficult sniper shot on the kidnapper. It was impressive. However, I did have something to say about that scene.

That's why I cleared my throat.

“I actually think that scene's kind of weird.”

“Weird?” Yozuki tilted her head to the side. “What's wrong with it?”

Well, Yozuki, I'm glad you asked. I straightened my back and puffed out my chest.

“You see, the main character, he snipes the enemy with a rifle, right?”

“Yeah, he punches a hole right in the bad guy's head.”

“But the gun he uses in that scene is an anti-materiel rifle, a Barrett M82.”

“An anti-materiel rifle?”

“It's a rifle made to shoot through armored vehicles and stuff,” I said. “In other words, it's a rifle that wasn't designed to shoot 'people', but 'things'. That's why, if you shoot someone in the head with an anti-materiel rifle, it wouldn't leave a nice, clean hole in the forehead like that. The entire head would have exploded. Brains would have gone flying everywhere.”

“Exploded head with brains flying everywhere.”

“Right, I mean, an anti-materiel rifle can shoot through a 20 mm steel plate. It wouldn't just leave a head intact. I hear if you hit someone in the torso with it, their body would fall apart like crumbly cheese.” 

“Crumble like cheese.”

“Yeah, that's why I thought the body was too pretty to have been shot with an anti-materiel rifle. It just wasn't realistic. It's a well-made film otherwise, so I wish they'd gotten that bit right.”

I stopped speaking so passionately when I saw Yozuki's stunned face.

“What are you talking about, Kasumi?” she reprimanded me. “There's no way they could show a scene where a person's head explodes or their body crumbles like cheese. I mean, it's a romance movie, isn't it?”

That was certainly true.

“Kasumi, you have absolutely no romance in your soul.”

Yozuki shrugged at me with an expression that said “This guy is beyond help.” She looked disgusted. Just was I was about to say something in my defense, she went “Oh.”

“I can see the island.”

She pointed at the horizon.

The shadow of our destination was visible beyond Yozuki's finger. And its strangeness made me gasp. I had researched the island before we left, of course, but seeing it in person was completely overwhelming.

The solitary island floating on the horizon was surrounded by a high fence. The fence appeared to be made of wire mesh. It stood 30 meters high and completely encircled the island with a diameter of about 500 meters.

Yozuki said the island's name.

“We've finally arrived at Wire Mesh Island.”

Wire Mesh Island had a mostly level surface, and in places it resembled a small forest covered in trees. A concrete wall about 50 cm high and 50 cm wide had been set up about a meter from the coastline, surrounding the island. The 30 meter tall fence, the most distinctive feature of Wire Mesh Island, protruded from the concrete wall. The mesh on the fence was in the shape of diamonds with sides of about 5 cm, and the view surrounded by the high fence gave the island the impression of being a fortress or a prison. It wasn't made like this by Otomigawara, the current owner, but by the obsession of Richard Moore, the great mystery writer who had previously owned the island.

Richard Moore was a British novelist who'd debuted in the 1920s during the Golden Age of Detective Novels, and was a legendary author on the same level as Agatha Christie, Ellery Queen, and John Dickson Carr. But what made him different from those other masters of the genre was that he'd been alive until quite recently. He'd only passed away in 2010, having lived to the age of 111. He'd spent his later years in Japan, on this Wire Mesh Island that embodied his ideals.

The name “Wire Mesh Island” had been given by Moore, who was an expert Japanologist. Its official name was “Full Moon Island”, but the name Wire Mesh Island had completely overtaken it. No one called it Full Moon Island. Apparently, even some maps listed it as “Wire Mesh Island” now.

That was why Wire Mesh Island was a sacred spot for mystery fans, but recently, it had become famous for another reason. After Moore's death, it had passed into the hands of a wealthy man, who sold it to the current owner, Otomigawara. That was only about half a year ago. So, why had that wealthy man decided to sell Wire Mesh Island to Otomigawara

Was he having money problems? No, that wasn't it. It was simply because he'd gone insane.

It had all started the year before last, and continued into last year.

Two years in a row, locked room murders had occurred in the small cottages on the island.

So, on this island, two people have already died in locked rooms.

There was only one entrance to the fence surrounding the island, and the ship docked at a pier built right through it. A surveillance camera was set up at the gate, and a young woman dressed in a butler's uniform stood next to it. She was tall and beautiful, with her black hair tied back.

When Yozuki and I got off the pier, the ship returned for the mainland without even saying goodbye. It wouldn't return to the island until four days later, at the end of Golden Week.

We crossed the pier and moved in front of the gate. The woman in the butler's uniform gave us a friendly smile.

“My name is Hitsujiko Toyama, a butler employed by Lady Otomigawara.”

She bowed her head at us. Yozuki and I panicked and also bowed at her.

I heard Yozuki murmur “Hitsuji-ko the shitsuji (butler).” Apparently it was a play on words. Yozuki had a habit of making puns to remember people's names.

Hitsujiko took a smartphone from her pocket, looked at the screen, and said “Mr. Kasumi Kuzushiro and Ms. Yozuki Asahina.” Apparently, the guest list was on her phone.

“Thank you both for coming, and welcome. Allow me to show you all around.”

Ms. Hitsujiko spoke with a proper, dignified smile. I tilted my head.

“Us all... what do you mean?”

“Of course, the other participants of the game. Everyone else has already gathered.”

Come to think of it, the other participants had already arrived the day before.

Ms. Hitsujiko turned on her heel and passed through the gate. Yozuki and I followed her and arrived on Wire Mesh Island.

When I checked my smartphone, it still showed out of range. It seemed there was no wi-fi here, either.

“The landline is usable,” Ms. Hitsujiko assured us. “Telephone lines connect to the mainland via underwater cables.”

“So we'll be safe as long as no one cuts the phone lines.”

Yozuki sounded like she was joking.

We moved along the coast, circling Wire Mesh Island. When I looked out at the wire mesh set up a meter from shore, I could see another island, very close to us. It was located north of Wire Mesh Island, only a few meters away. Although it was also very flat and level, it did have one hill at the northern tip, about 40 meters above sea level, with a mansion facing the sea built atop it. The mansion was about 500 meters away from us, but since it was a large Western style manor, I could make it out easily.

“What's that island?” I asked.

“It seems that island was once owned by a wealthy man,” Ms. Hitsujiko answered. “It's deserted now, however. I've never seen the mansion's lights on.”

“Hmm, it's pretty big,” Yozuki said.

“The island has a length of approximately 500 meters,” Ms. Hitsujiko said. “When viewed from the air, it resembles a crescent moon. That is why the island is called Crescent Island.”

That was easy enough to remember. The official name of Wire Mesh Island was Full Moon Island. Full Moon Island and Crescent Island. It felt right, somehow.

As I walked along the sandy beach, I turned away from the sea. I saw cottages dotting the landscape here and there. There were many different types, from traditional log cabins to ones made of stone and brick.

“There's a lot of cottages,” I said.

“I am told they were all built by the mystery novelist Richard Moore,” Ms. Hitsujiko replied.

As we walked along like that, we passed a cottage built on the sandy beach. A tent was pitched out in front of the cottage. It looked like someone was camping. Thinking that, I kept walking, when I eventually caught sight of a girl lighting a bonfire. Apparently there was someone camping. Then, apparently just noticing us, the girl turned her eyes to our group.

The girl was white. I don't mean she was a foreigner; her hair, skin, and dress were all the color of unpainted porcelain. However, her eyes were red. Was she an albino? No, albinos were sensitive to sunlight, so one wouldn't camp out on a beach. So what was she...?

The snow white girl was basking in the heat of the bonfire, looking at us as though assessing our worth. She was around middle school age. She had long hair tied in twintails, which, combined with her beautiful features, gave her a mysterious aura.

The girl stared at us for a while before beckoning us over. Yozuki and I approached her as though we were being drawn in. Then, the girl picked up a skewer that had been toasting a marshmallow over the bonfire and pointed it at me.

“Here,” the girl said. “I'll give you this.”

Huh? Why, though? The girl laughed mockingly.

“Need I a reason to give you a toasted marshmallow?”

No, I just didn't think it was necessary.

“Just take it, Kasumi,” Yozuki said sympathetically. “Otherwise she'll throw a temper tantrum.”

“Don't treat me as though I were some pitiful child! This is enough for you, madame.”

The girl picked up another skewer that had been over the bonfire and pointed it at Yozuki. Yozuki looked at the food on the end and asked in confusion.

“Um, what is this?”

“It's a toasted gummy.”

“...Toasted... gummy.”

Yozuki looked like she'd lost all hope.

“Is that Haribo cola?”

“Ah, I see you have a sharp eye. Perhaps you do have some value. Then did you know that the flavor of Haribo cola makes for the most delicious toasted gummy in all the world?”

“I didn't want to know that!”

Yozuki looked on the verge of tears as she accepted the impaled gummy candy. Then, hesitantly, she put it in her mouth. She was a curious woman. Yozuki's face contorted. Then, she opened her eyes.

“Oh, it's good.”

It was? She was definitely lying.

“Um, are you sure?”

I asked with confusion plain in my features. The girl had “I told you so” written all over her face. She gently placed one palm over her chest as she told us her name.

“I am Emiri Sotodomari. I am a vampire who has lived for a thousand years.”

Well, it was easy to tell she was a weirdo.

“Emiri Sotodomari,” said Yozuki. “Sotodomari is soto ni tomatte (staying outside).”

She did appear to be sleeping in that tent.

“She's also a vampire...” Yozuki muttered to herself and for some reason she appeared to be thinking seriously. Eventually, she started and said something surprising.

“It's you! You're the chupacabra of Wire Mesh Island!”

My god! It was all coming together!

“No I'm not.”

My god! She'd denied it immediately!

“To begin with, vampires and chupacabras are completely different beings. They are as distinct as a bat is from an axolotl.” That was very distinct. “Besides, I've never heard of any chupacabra living on Wire Mesh Island. Where did you hear such an absurd story?”

Yozuki immediately started crying.

“But... But Mu...”

Maybe it was time to start regarding that magazine with a bit more skepticism.

Sotodomari gently handed Yozuki a toasted marshmallow. Yozuki took it and ate it, crying the entire time.

Group composure regained, I asked a question. 

“By the way, why are you out camping in a place like this?”

Sotodomari stroked her white hair and said “You ask the most obvious questions.”

“The truth is simple. Naturally, it's because camping is my hobby.”

“Camping is your hobby.” I repeated, raising an eyebrow. “Even though you say you're a vampire.”

“I don't 'say' I am, it is the truth.”

“Ms. Sotodomari is a friend of Lady Otomigawara,” Ms. Hitsujiko said.

“Ah, right,” Sotodomari nodded. “Otomigawara invited me to visit for Golden Week. Since it would be boring to simply remain in a cottage the whole time, I chose to pitch a tent out on the beach. This island is a most excellent place for camping. The cottage provides running water for showers, so it's almost like a private campground.”

Something about that struck me.

“Does that mean you aren't a participant in the game?”

“Game? Oh, you mean that Locked Room Trick Game,” Sotodomari said. “It sounds like a grand time. I wished to join, but Otomigawara denied me.”

“Is that so?”

“Agh, and she was so bossy when she said it,” Sotodomari said indignantly, then put on a voice that was probably supposed to be an impression of Aoi Otomigawara. “'Unfortunately, Sotodomari is not eligible to participate. For only those selected as detectives can participate in the game.'”

After we parted ways with Sotodomari, we walked along the beach for a while longer and arrived at a stone staircase leading to an asphalt road. It was a two-lane road, and as we made our way down it, I saw a bright cherry tree to my right.

That's right... there were cherry blossoms. Even though it was already May, the cherry tree was still in full bloom. Since the blooming period was over, it probably wasn't a Somei-yoshino, but it was just as beautiful.

“Wah, it's beautiful,” Yozuki said. “It's so romantic.”

“Yes, it is beautiful,” Ms. Hitsujiko. “It's a special cherry tree called a Somei-harukano, and there are only a dozen in the world. And one of them is here, on this island.”

“Wow, that's rare.”

I looked up at the cherry tree as I expressed my agreement. It was a large tree about 10 meters tall, and it had a beautiful canopy that blocked out the sky. I thought the petals had more of a red color to them than a Somei-yoshino's. When I said that, Ms. Hitsujiko said “That's correct.”

“After all, it has drank human blood.”

Well that was ominous.

“Huh? What are you talking about?”

When I asked that, Ms. Hitsujiko immediately pointed to the other side of the cherry tree. Past the tip of her finger, I saw a cottage standing about ten meters away from the shadow of the tree. It was as though it had been hidden by the tree's radiance.

It was a metal cottage in the shape of a rectangle. A square grid pattern was carved on the walls, making it look like a giant Rubik's Cube. The exterior walls were made of silver, polished to a mirror sheen.

I asked Ms. Hitsujiko.

“What's with that cottage?”

Ms. Hitsujiko replied “Oh? You didn't know? I believed that the locked room murders that took place on this island were common knowledge.”

Her words took me aback.

“You mean the two locked room murders that took place on this island before...”

“Yes, they both took place in that cottage.”

Instantly, I felt fear growing in my heart.

There had been two locked room murders on this island in the past. The first occurred the year before last, and the second was last year. Both had occurred in May, in the season when the blood red cherry blossoms were in full bloom.

“Indeed, both incidents happened during the cherry blossom season,” Ms. Hitsujiko said. “That gave birth to a certain legend. If you stay in this cottage while the cherry blossoms are in full bloom, you will certainly be murdered in a locked room. You will be decapitated and killed, just as they were.”

Her words reminded me of the news article I'd read. Indeed, both of the victims had been decapitated. And not posthumously, but alive. Their heads had been cut off by a sharp blade.

Of course, there was no way to decapitate them inside the locked room.

That was why those locked room murders were so perfect that the awestruck population had given them a name.

“One of Japan's Four Great Locked Rooms,” I said. “The Decapitation Chamber of Wire Mesh Island.”

Japan's Four Great Locked Rooms – starting with the first ever locked room murder in Japan three years ago, the First Locked Room – were the four most impenetrable locked room murders in Japan.

Of course, I knew about it, but seeing it with my own eyes was incredible. No, that probably wasn't the right thing to believe. But as a mystery fanatic, I couldn't help but be drawn to it.

“I don't really get the whole Japan's Four Great Locked Rooms thing,” Yozuki said. “Is it really true that a locked room murder always happens during the cherry blossom season? Isn't that just a coincidence?”

“The sample size is too small,” said Ms. Hitsujiko. “There have only been two locked room murders, so it could easily be called a coincidence. Even though I'm the one who said it, I don't necessarily believe in it myself. But I like these kinds of urban legends and rumors, so I can't help but want to share them with others.”

Ms. Hitsujiko smiled shyly. When she saw it, Yozuki said “Hmm, that's an unusual hobby.” I wondered where a woman who'd come to a solitary island hunting for chupacabra got off saying that.

“However...” Ms. Hitsujiko continued. “No matter how superstitious it may sound, it is still dangerous. That's why I don't recommend staying in that cottage during cherry blossom season. If something happens, it will be too late. But...”

For some reason, Ms. Hitsujiko hesitated.

At that moment, the cottage's door swung open. A chubby man in a Sherlock Holmes cosplay appeared from inside. I couldn't help but turn to Ms. Hitsujiko in confusion and ask her.

“He isn't staying there, is he?”

Ms. Hitsujiko raised her eyebrows, apparently confused herself.

“I told him not to do it.”

Seriously?

I looked at the man who'd come out of the cottage, nakedly confused. He was probably in his mid-30s. He had a mustache, and even though he was overweight, his features were well defined. If he slimmed down, he'd probably be quite handsome.

As I was thinking things like that, Yozuki, standing next to me, suddenly started.

“Is that... Kosuke Poirotzaka?” 

What? I though. Yozuki looked at me like I had two heads.

“I can't believe you, Kasumi. Poirotzaka, the Youtuber Detective.”

“...So who is he?”

“Kasumi, you have no common sense.”

“Please don't talk about common sense when discussing youtubers.”

What I wanted to know is why, if his name was “Kosuke Poirotzaka”, he was cosplaying Sherlock Holmes and not Kosuke Kindaichi or Hercule Poirot.

“By the way, why is Poirotzaka staying in such a creepy cottage?”

When I asked Ms. Hitsujiko that, Poirotzaka himself appeared to hear us and ran over.

“Ah, I am the proprietor,”

He actually said “proprietor”,

“I am the proprietor of a YouTube channel called 'Poirotzaka Authentic Mystery ch.' I have a very popular series where I visit and stay at mysterious spots associated with urban legends.”

“Are you planning to spend the night in a mysterious spot?”

“Ah, the video's title will be 'I Stayed In A Real Mystery Novel House!? – Great Detective Poirotzaka'.” Poirotzaka said proudly. “That is why I chose this cottage. In summary, the plan is to stay in this building during the cherry blossom season and see if it actually kills me.”

“That's a pretty extreme plan.”

“If it's not extreme, it's not worth doing. I don't want to be like other youtubers, only uploading mediocrities to the web.”

Was that how it was? Apparently he thought so.

“Oh, I watch all your stuff! It's so exciting!,” Yozuki cheered. “Risking actual, literal death for the sake of content, it's so cool!”

I wondered what sort of audience he'd cultivated.

“Did you even get permission to record here?” I asked. “I mean, this is private property, right? I'm surprised Ms. Otomigawara, who owns this entire island, would agree to something like this.”

“Ah, that is to say...”

“Of course, she has her reasons,” Ms. Hitsujiko replied on behalf of Poirotzaka. “In truth, Mr. Poirotzaka is also a participant in the Locked Room Trick Game. So, as an exchange condition, Lady Otomigawara granted him permission.”

So in other words, in exchange for participating in the game, he was allowed to stay in that cottage.

“Well, that is the length of things,” Poirotzaka said with a nod. “In short, for one such as myself, this game is but a mere trifle. Although, since I am being forced to participate either way, I may as well take my victory.”

So saying, Poirotzaka took a pipe from his pocket and lit it with a match. A massive amount of smoke flowed out, which seemed out of place in the modern age.

“Mr. Poirotzaka, it is time to head to the mansion,” Ms. Hitsujiko said with a look at the clock.

“Ah, I suppose it is.”

After letting out a puff of smoke, Poirotzaka turned back towards his cottage.

“I must prepare some things. Please, do go on ahead.”

Poirotzaka said that and went inside the cottage.

After we parted ways with Poirotzaka, we walked for five more minutes and finally arrived at our destination. The island was about 500 meters in diameter, and we'd gone from north to south.

Our destination was a large three-story mansion located on the southern end of Wire Mesh Island. The mansion was built on a sheer cliff several meters high, and beyond the cliff was nothing but the sea and the fence. A tower stood next to the mansion. It was fairly tall, its top standing about 10 meters above the top of the 30 meter fence surrounding the island.

“The room at the top of the tower,” Ms. Hitsujiko said, “is the only place on the island above the fence. In other words, it is the highest point on this island. That's why it is called the Tower of Heaven.”

That was a dramatic name.

“Please, enter.”

Guided by Ms. Hitsujiko, we entered the mansion. The view that spread out before us a spacious entrance hall that truly belonged in the mansion of a billionaire. There were vases and paintings, as well as a giant sword that appeared to be about 3 meters long. It looked like something out of a fantasy anime. And next to it was a silver suit of Western armor. It was a suit of full plate, with a helmet that completely hid the face.

“Wow! Cool!” Yozuki ran up to the armor, looking like she'd relapsed into her chuunibyou phase. “It's a real antique. It looks expensive.”

“It most certainly was expensive,” said Ms. Hitsujiko. “But it is not a real antique armor. It was made quite recently. Even the great sword that appears to be forged of iron is actually made of a special alloy.”

“Hmm, so it's alloy,” I said. That actually made me more interested. “What kind of alloy is it?”

“It is an alloy five times stronger than steel, developed by Lady Otomigawara's company, Otomigawara Industries,” Ms. Hitsujiko said with some pride. “Actually, the cottage where Mr. Poirotzaka was staying earlier is made entirely of the same alloy as this sword and armor.”

“Huh? But that cottage has been there since before Ms. Otomigawara bought the island.”

After all, she had only acquired the island half a year ago. By then, two locked room murders had already taken place in that cottage.

Ms. Hitsujiko answered my question.

“Yes, that cottage was constructed by this island's previous owner, the mystery novelist Richard Moore. In truth, Mr. Moore has been a long time associate of Otomigawara Industries, and it was through that connection he was able to purchase the material for the cottage from our company. That was over ten years ago – about six months before Mr. Moore's passing.”

I nodded in response to her explanation. That got me thinking about the locked room murders that had previously occurred on this island. 

“Whoa, it's light,” Yozuki said, picking up the helmet of the armor. “As expected of an alloy.”

I also tried lifting the helmet. Even though it was about a centimeter thick, it was indeed quite light.

When we passed through the entrance hall and went through a door, we arrived at a short hallway. At the end was another door. When Ms. Hitsujiko arrived at it, she turned back to us and spoke.

“This will be the venue of the game.”

Ms. Hitsujiko opened the door. On the other side was a salon with a tranquil air about it. Three people were already gathered inside.

One was an old man in religious garments. Another was a blonde man who was wearing a fur coat even though it was May. The third was a beautiful woman in her late twenties.

Two men and a woman – were they participants in the game? As I was asking myself that, I felt someone's presence behind me. When I turned around, I saw Poirotzaka, who walked past me into the salon as though it were his own home.

Including myself, there were now seven people there. Five if we excluded Yozuki and Ms. Hitsujiko. We all exchanged glances, scrutinizing the competition. After a while of that, the atmosphere of suspicion was broken by a door in the back of the salon opening.

What appeared from it was a woman of good breeding with long chestnut hair. She had handsome features and large, curious eyes, and wore a puffy, pure white dress that made her look like she'd just come from a foreign aristocrat's mansion. As for her age, she could only have been 24.

“Aoi Otomigawara.”

I whispered her name. One of the richest people in Japan. Although she didn't get that much media exposure, I had seen her on TV and in magazines a few times.

Otomigawara looked at us and smiled.

“Thank you all for coming today. I am Otomigawara, the owner of this island.”

After announcing herself, she bowed at a flawless 90 degree angle. Then she said “Now then,” and looked at everyone gathered in the salon.

“With the formalities out of the way, allow me to tell you why I've invited you all to this game. Despite my appearance, I have always been a lover of great detectives. I wanted to invite some to my abode. But just inviting them wouldn't be enough fun...”

“So you decided to make us play games for prize money?”

Poirotzaka finished her sentence and deduced her intentions. Otomigawara put on the face of a child who'd been caught committing a prank.

“It's a good idea, isn't it?”

Poirotzaka stroked his mustache.

“Perhaps it is, but isn't this rather heartless? Even if you won't say so, it's obvious enough I am the greatest among us.”

“Oh well you are confident, aren't you?” said one of the guests, the blonde man in the fur coat. “As expected of Kosuke Poirotzaka, the popular youtuber. I won't say anything bad about you, but wouldn't it be for the best if you just gave up and ran away now? I'd hate to have to ruin the reputation you've spent so long building!”

Poirotzaka avoided the man's gaze and ignored his comment. The blonde man looked very sad.

“Don't ignore me...”

“What about the selection?” Poirotzaka asked Otomigawara, still ignoring him. “How did you choose the participants for this game. We find ourselves living in the Golden Age of Locked Rooms, so there are many great detectives to choose from. How did you select from amongst them this assemblage? Purely out of curiosity, you see.”

“Seriously, I'm right here...”

“We tried to gather as diverse a selection as possible,” Otomigawara replied. “I have an online friend who calls himself 'The Lord of Locked Rooms'. When I told him I was thinking about inviting a gathering of great detectives to this island and was wondering what sorts of people to invite, he came up with a list of members. There was a great variety, including people I would have never thought to invite. I was so impressed that I made the decision right away.”

In other words, it was a scattershot selection, and Otomigawara herself had no involvement in it. The guest list was solely the work of the Earl of Locked Rooms.

“I see, what an interesting story,” said the blonde in the fur coat, nodding. “And the selection itself is quite interesting. Or rather, I would call it perfect. Why is that, you ask? It's obvious. For one reason and one reason alone. Among those gathered here is 'me'. That alone makes this selection perfect.”

Otomigawara ignored him.

“You're ignoring me too?”

“Just kidding.”

“Why are you all being so mean...?”

The blonde in the coat had tears in his eyes.

After apologizing with an unapologetic smile, Otomigawara looked at the group and made a suggestion.

“Now then, before I explain the game itself, I'd like everyone to briefly introduce themselves. First off... Mr. Otozaki.”

Otomigawara turned her attention to the blonde in the fur coat. He happily announced “Alright, here I go!”, then announced his name.

“My name is General Otozaki, and I am a detective singer-songwriter. Most of my songs are about locked rooms. You all have probably heard my most famous song, 'She Was Killed In A Locked Room'.”

I actually hadn't. Looking around, it looked like no one else had, either. Otozaki looked very lonely.

Seeing him like that, Yozuki nodded.

“Mr. OTO (sound)-zaki is a musician, then.” After finishing her punning, she tilted her head to the side. “Huh? But, wait, if you're a musician, then why were you invited to this detective game?”

“Mr. Otozaki is both musician and detective,” Otomigawara explained. “If I recall correctly, you came in eighth in last year's 'This Locked Room Detective is Amazing!' rankings, correct?”

I see... Then he must be talented.

Locked room detectives are detectives who are licensed to investigate locked room murders on behalf of the police, a new profession created for the Golden Age of Locked Rooms. “This Locked Room Detective is Amazing!” is a magazine published twice a year containing a ranked list of locked room detectives. Placing anywhere in the top ten makes you one of the best in the industry.

“Then, would you like to introduce yourself next, Mr. Poirotzaka?” Otomigawara asked, turning to the man in question.

Poirotzaka nodded. After twirling the tip of his moustache between his fingers, he opened his mouth and said:

“I'm Kosuke Poirotzaka. That's all.”

Having said that, he stroked his moustache again and went silent. Even Otomigawara looked confused.

“Is that all the introduction you have?”

“What more is there to say?” Poirotzaka said, looking annoyed. “I didn't need to introduce myself at all. There isn't a person left in Japan who doesn't know my name.”

I was there, I think.

But Otomigawara said “That's certainly true.” The gap in my knowledge was huge. Perhaps Poirotzaka was as famous as he said.

“Now then, next,” Otomigawara ended Poirotzaka's introduction and chose who would go next. “Mr. Anthony, if you would.”

The old Caucasian man in the religious garments nodded solemnly. He appeared to be in his mid-60s, but was still strong and dignified. His gray hair was slicked back, he wore round, silver-rimmed glasses, and he had a gentle smile that showed no malice.

The old foreigner spoke fluent Japanese.

“My name is Anthony Gentleman. As is clear from my attire, I am a religious man by trade. I am an executive of the organization known as Tower of Dawn.”

Those words sent the air buzzing.

Tower of Dawn was a religious organization that had rapidly expanded its influence in Japan following the beginning of the Golden Age of Locked Rooms. It was understood by the general public as a so-called “religion that worships locked room murders”. To be precise, what they worshiped wasn't locked room murders, but the scenes of locked room murders; photographs of crime scenes were their sacred objects. Their doctrine went that purifying the grudges trapped in the scene of a locked room through prayer turned the negative energy into positive, achieving happiness.

The old Gentleman was definitely wearing the religious garments of Tower of Dawn, so even before he introduced himself, it was obvious that he was affiliated with the cult. However, he'd said he was an executive of the group. The executives of Tower of Dawn were called the Five Archbishops, and they were the candidates to become the next High Priest – in other words, they were a big deal. Looking at him with that new information, I couldn't help but think there was an unusual aura about him.

In such a tense atmosphere, Yozuki could still speak freely.

“He certainly is a dignified old Gentleman.”

But he was significantly more than that.

“Now, let's hear our next guest's introduction.”

Otomigawara looked straight at me. “Right, my name is Kuzushiro,” I said, and nervously said a few things about myself.

“Thank you for the introduction, Mr. Kuzushiro.” Otomigawara gave my introduction a small applause. “Then, would our next guest please speak up?”

Otomigawara turned to the last person left to speak. She was a woman in her late twenties with short hair, casually dressed in a turtleneck and jeans. And her face was quite well proportioned.

The beautiful woman spoke in a cool voice.

“My name is Chiyori Kurokawa. I am a lawyer by profession, but due to circumstances I was forced out of the industry, so now I'm practically unemployed. I used to be a judge at the Tokyo District Court, but I had to retire a year ago.”

Her words sent the entire room buzzing. Chiyori Kurokawa... Of course we all knew her name. In fact, she was probably the most famous judge in the history of Japanese law.

In the winter of three years ago, she'd been in charge of a murder trial, and her verdict had changed the very nature of crime in Japan. That wasn't an exaggeration; that was just what had happened.

I stared at Chiyori Kurokawa, the origin of the Golden Age of Locked Rooms. Of course, this was our first time meeting, but I knew her face well from the time when interviews with her were a common sight on variety shows. Then as now, she was an amazing beauty. Despite that, he hadn't recognized her until now, probably because her once-long hair had been cut short.

“Now that we are all finished our introductions,” Ms. Hitsujiko said, trying to calm the room. When she didn't particularly succeed, she coughed slightly. “Allow us to begin explaining the game. As written in your invitations, the game you are being asked to challenge is called the Locked Room Trick Game. The rules are-”

“No.” Otomigawara suddenly cut off Ms. Hitsujiko. Then, she pompously declared “It is too early to begin the game.”

Ms. Hitsujiko looked troubled.

“What do you mean?”

“It's obvious. A participant still hasn't arrived.”

“Huh? But...” Ms. Hitsujiko looked around, confused. “There should be a total of five participants, no? In that case, everyone is already here.”

“Actually, I secretly summoned an additional person,” Otomigawara said happily.

She'd summoned a surprise guest? I'm pretty sure that she ship we'd come on hadn't had anyone like that. Did that mean that Otomigawara had arranged another boat and invited them without telling Ms. Hitsujiko?

“Oh?” Otomigawara turned to the entrance door to the salon, the one connected to the hallway. And a childlike, innocent smile appeared on her lips.

“It appears they just arrived.”

Just as Otomigawara said that, the doorknob moved.

The person who opened the door was a young male butler. A girl followed behind him.

I couldn't keep my voice down.

She was an incredibly beautiful girl with long black hair down to her waist. She had large, almond-shaped eyes that gave off a cool light.

“Shitsuri... Mitsumura.” 

I spoke the name of my classmate.

What was she doing here? I was confused for a moment, but then I felt stupid for having asked.

What was she doing here? It was the exact opposite. Why had I ever thought she might not have come?

Because if what was about to come was a game of locked rooms,

Then we couldn't possibly have started without her. Because in this world, there is no one more suited to the idea of “locked rooms” than the girl known as Shitsuri Mitsumura.

“Proof of non-resolution of a locked room is equivalent to proof of absence from the scene of a crime.”

Three winters ago, a girl in her second year of middle school was arrested on suspicion of killing her own father. Given the evidence found at the scene, there was no doubt that the girl was the culprit, but at the trial, she was found not guilty. Why? Because the crime scene was a locked room.

Three years ago on a winter day, Japan's first locked room murder was committed.

The suspect's name was Shitsuri Mitsumura. The girl who was once my classmate.

Everyone in the room was clearly excited by Mitsumura's surprise appearance. Gentleman was staring at her in shock, and the musician Otozaki murmured “Shitsuri Mitsumura” in total disbelief. Everyone else was reacting similarly.

It probably goes without saying, but they all knew about her. The culprit of Japan's first locked room murder – or, given that she was, in fact, acquitted, should I call her the defendant? Either way, Mitsumura was the prime suspect, and almost all Japanese people believed she was the real murderer. The evidence presented by the prosecution was perfect – but that perfection was rejected by the stupidest verdict in history, and the single judge who forced it through.

An outrage, committed by then-Tokyo District Court judge Chiyori Kurokawa.

As a result, Japan entered the Golden Age of Locked Rooms, where locked room murders were committed at a rate of over 100 per year, and Shitsuri Mitsumura doubtlessly sat at the center of the era.

However, since Mitsumura had still been a minor at the time of the crime, her real name had been kept out of the media, but there were some enthusiasts who had managed to track down her real name and face. And it seemed that all of the participants in this game were that sort of enthusiast.

Mitsumura looked around at the commotion she'd caused, and her eyes met another person's. It was Chiyori Kurokawa. Mitsumura gasped. Kurokawa also narrowed her eyes at the girl. It must have been completely unexpected for both of them, but the defendant and the judge had been reunited here. Everyone around them noticed and began making even more noise.

However, Yozuki, who didn't seem to understand the dramatic situation, turned blankly to me and asked “Hey, Kasumi, what's going on? Is Mitsumura famous?”

Come to think of it, Yozuki didn't know about Mitsumura's past, did she? I said the first lie I could think of: “Mitsumura was a famous magazine model in middle school.” Yozuki said “Huh. Cool.” I was getting a little worried about her. Would this girl really be able to survive on her own?

“Now that all the pieces have gathered, we can start the game,” said Otomigawara. “Then, Shitsugi, please take care of everything.”

Otomigawara was referring to the male butler who'd accompanied Mitsumura into the room. He was a tall, strongly built young man in his mid-twenties, and he bowed at us once before introducing himself as Koichi Shitsugi.

“So the other shitsuji is Mr. Shitsugi,” Yozuki said. That made me pause. So there were two butlers on the island, Shitsugi and Ms. Hitsujiko.

“Now, allow me to explain the game to you all,” said Shitsugi, who'd been assigned as the game's host. “As written in your invitations, the game we are asking you to play is called the Locked Room Trick Game. As the name suggests, it is based around locked room tricks. Ms. Hitsujiko, if you would?”

When Shitsugi turned to Ms. Hitsujiko, she took a stack of papers from the corner of the room and distributed them to everyone. On them were written the rules to the Locked Room Trick Game.

Rules of the Locked Room Trick Game:

① Once a day, the participants draw lots to determine who will be the day's culprit.

② The player chosen as the culprit commits a “murder” and makes the crime scene into a locked room.

③ All players who do not have the role of culprit play the role of detectives.

④ The detectives' goal is to solve the locked room created by the culprit.

⑤ If a detective manages to solve the locked room, that detective gains 3 points.

⑥ If the locked room is not solved by sunset that day, the culprit gains 5 points.

⑦ This repeats for five days. The player with the most points at the end is the winner.

⑧ If a locked room is solved, the culprit will be imprisoned and excluded from the game for three days.

⑨ The person playing the role of culprit will not be penalized for being exposed as the culprit, so long as their locked room remain unbroken.

⑩ Because the role of culprit is distributed entirely by lottery, it is possible for one player to be given the role of culprit multiple times, and another player to never be chosen even once.

“...”

I read and reread the paper I'd been given several times, making sure I completely understood the rules. Although there were many rules, the game itself was simple. The culprit earned points by creating locked rooms no one could solve, and the detectives earned points by solving locked rooms – that was it. If you were the culprit, you could earn five points in a day, so at a glance it might have looked more advantageous to be chosen by the lottery. However, there was a penalty, and if you failed, you wouldn't be able to participate for three days. Given the game only lasted five days, not being able to participate for three of them would make it extremely hard to win. That made me feel that being chosen as the culprit was extremely risky.

“May I ask a question?”

The person who'd raised his hand was the old Gentleman, the executive of Tower of Dawn. He asked Shitsugi without looking up from the paper with the rules written on it.

“It says here that the player chosen to play the role of the culprit will carry out a 'murder', but how exactly will they do it? They won't actually kill someone, will they?”

Shitsugi answered him “Of course not.” When he and Ms. Hitsujiko exchanged a look, she retreated into the back room and returned carrying a large stuffed polar bear.

“Aw, cute!” Yozuki said. 

Aw, cute, indeed. But that stuffed animal was probably...

“This stuffed animal will play the role of the victim.”

Shitsugi said exactly what I'd expected. Yozuki looked shocked by his words. “It's so cute, though,” she lamented.

“Shall the culprit be permitted to forge their locked room in any chamber?”

That was Poirotzaka. Shitsugi nodded and said “Yes, any room in the mansion.”

“However, we would ask that you avoid using Lady Otomigawara's private room. If you are chosen to play the role of culprit, please consult with one of us which room you've chosen to turn into your locked room. We will lend you the key, as well as any tools necessary for your trick, such as needles, ice, or string.”

“Setting aside ice and string, I can't imagine anyone would be daft enough to use a needle trick in the modern era,” Poirotzaka said with a sneer. Then he said “I understand the rules. You may continue.”

Permission given, Ms. Hitsujiko picked up a stack of envelopes that had also been in the corner of the room. She spread them out in a fan shape and approached Poirotzaka first.

“These are the lots we will use to determine the culprit. Please, pick one.”

Poirotzaka took an envelope. One by one, we all pulled our lots from the stack.

That included me. When I secretly stole a peek inside, I saw a blank sheet of paper inside.

“The culprit's envelope contains a piece of paper with the word 'culprit' written on it,” Otomigawara said. Apparently, I wasn't the culprit.

“Then, everyone, please walk this way.”

Shitsugi opened the salon door and indicated for everyone to follow him into the hallway. He guided us further down the hall to another hallway with a number of doors lined up.

Then, he opened a door. Inside was a simple, eight tatami mat room.

“There are several rooms with identical floor plans to this one in this section of the manor,” Shitsugi said. “Everyone will now wait in these rooms for an hour while the culprit commits their crime.”

“I see, so we all spend this hour in separate rooms,” said Gentleman. “Does that mean only the culprit can leave their room? And after committing their 'murder', they'll return to their room with an innocent look on their face. In that way, the other players... the other 'detectives' won't be aware of the culprit's identity.”

“That's correct,” Otomigawara said happily. “It's helpful that you all catch on so quickly.”

Gentleman shrugged, looking playful himself. Then he looked at the eight tatami room and said “In that case, I'll take this room.” He entered the room.

The door shut behind him.

Shitsugi began leading the other players to their respective rooms one at a time. I took the opportunity to talk to Mitsumura.

“Why are you on this island?”

Mitsumura raised her eyebrows in response.

“I believe that's my line. Why are YOU on this island?”

“Good question.” As she'd said, it was a total mystery why I'd been invited. I was completely different from Mitsumura, whose presence was totally natural. But that wasn't what I'd been concerned about...

“No, I was wondering why you accepted the invitation.”

Naturally, Mitsumura spent her life hiding her past. She even went so far as to attend school under the pseudonym “Matsuri Natsumura”. I didn't understand why she'd accept this invitation.

Mitsumura said “I'd think that would be obvious.”

“I want that billion yen prize.”

She said that with total confidence.

“I had no idea you were so greedy.”

“Oh? Kuzushiro, do you call people who buy lottery tickets 'greedy'?”

“No, I don't.”

“Then your accusation is wildly off-base.”

And then Mitsumura shrugged her shoulders before showing me a teasing smile and saying “I'm just kidding.”

“To be honest, I came to this island because I found the invitation so annoying. I was hoping to tell Ms. Otomigawara not to do anything like this again. But as soon as I arrived, she announced the start of the game and I didn't get my chance to complain, which is troublesome.”

Mitsumura gave a tense, angry smile. At that moment, Shitsugi called for “Ms. Mitsumura.” He guided her to her room.

“See you later, Kuzushiro.”

Mitsumura waved at me as the door shut. Now I was the only guest left in the hall, except for Yozuki who wasn't playing the game.

“Then, Mr. Kuzushiro, come this way.”

I also entered the room I'd been assigned.

Immediately after everyone entered their rooms, one of the doors opened and a certain person emerged. It was the “culprit” of the game. The “culprit” called out to Hitsujiko and told her there were some items they wanted prepared. “Yes, what is it?” she responded, opening the notepad app on her smartphone.

“A remote controlled car? And also a clothespin, a length of rope, kite string, duct tape, and an office chair with casters? Yes, I'll have it prepared right away. Please wait a moment.”

Every volume of Death Note and Fullmetal Alchemist were there in the room, so I decided to read to kill time until the culprit finished setting up their locked room. About an hour later, someone suddenly started banging on the door. When I hurriedly opened it up, Ms. Hitsujiko was there, pale faced and haggard.

“It's terrible, there's been a murder!”

I was taken aback.

“What!? Someone was killed!?”

When I said that, Ms. Hitsujiko looked embarrassed and said “Ah, no.”

“...It was just part of the game. No one actually died.”

Ah. I see, I think.

When Ms. Hitsujiko led me to another room of the mansion, all the game's participants were already gathered there.

And there was a piece of paper pasted to the door, which read

“There is a corpse in this room. The victim, the polar bear, has already lost his life.”

I looked at it in thought.

In other words, this was the scene of the first round of the Locked Room Trick Game.

I asked Shitsugi something.

“Are there any other keys to this room?”

“There are no duplicate or master keys, and even if there were, it wouldn't matter,” Shitsugi said. “You see?”

He pointed to the door to the room. There was no keyhole of any kind anywhere on the door. I see... this was the sort of door that couldn't be locked from outside of the room.

“Hmm... Then does that mean the culprit sealed this chamber from within?”

Poirotzaka said that and gave the doorknob a rattle. Seeing him, I decided to check to make sure it was locked as well. When I pushed forward on the doorknob, I distinctly felt the deadbolt hit the door frame. The door was definitely locked.

I asked Otomigawara something.

“Can I break down this door?”

Otomigawara replied with a grin.

“I don't mind... if you can.”

That was motivating. I stepped back and slammed the door as hard as I could. And when I did, my face twisted in pain. This door was extremely hard. I don't think I could have broken it down with anything short of an axe.

“It would be faster if we went around to the window,” Mitsumura said softly.

Immediately, someone dashed off. It was Poirotzaka. Despite his chubby appearance, he was a fast runner.”

“Trying to get ahead of us, are you?”

After saying that, Gentleman ran off after Poirotzaka. I followed him. As if that was the signal, the rest of our group also ran off. Otomigawara, the organizer, ran alongside us, overcome with curiosity.

“Why is everyone running?” asked Yozuki, who was running next to me.

Out of breath, I replied “Because you have an advantage if you arrive at the scene first.” After thinking on my words for a moment, Yozuki was convinced.

“I get it. If you get there first, you can be the first to get the information. That's an advantage.”

That was true, but...

“I think everyone else is afraid of something.”

“What do you mean?”

“The first person to arrive might hide some evidence from the scene so the other players don't know about it. That would mean there wouldn't be enough material left to make a correct deduction, right? As a result, the other players wouldn't have a chance to uncover the trick, and the player who'd hid the evidence would have a major advantage.”

In short, the first player to arrive at the scene had a chance to interfere with the other players.

When I turned the corner of the hallway, following the others' backs, I saw the entrance. We went outside and followed the wall to the window of the room where the “murder” had taken place.

The window was fixed. In other words, it couldn't be opened or closed. When I looked into the room, I saw, the stuffed polar bear playing the victim role lying on the ground. A knife was stuck deep in its chest.

“Oh, how terrible,” Yozuki lamented. “Poor thing.”

It was a pretty sorry sight.

But either way, I needed to get into that room and examine the polar bear's corpse(?). And the only way to do that was to break the window. As I was thinking about how to do that, I heard footsteps from behind. When I turned around, I saw Mitsumura with a mop in her hand.

“Kuzushiro, move.” Mitsumura brandished the mop like a spear. Then she looked at Otomigawara and said “I'm going to break the window. Do you mind?”

Otomigawara still sounded happy.

“Breaking the window is standard in a locked room murder. Please, feel free.”

“Well... If you say so.”

Mitsumura jabbed the mop and broke the glass. She repeated this several times until there was enough space for her to grab the window frame and vault through.

She was surprisingly athletic. I climbed over the frame and followed her into the room. The other participants also crossed the threshold one by one. As we approached the sadly skewered stuffed polar bear, we noticed “it”.

“Mitsumura, look.”

I pointed at the stuffed bear. A key had fallen there. I approached the stuffed animal and picked it up.

“This is...”

“Is that the key to this room?”

Mitsumura turned her eyes to the door to the room. The door didn't have a latch or thumb turn; it had a keyhole on the inside. In other words, the culprit had put the key in the lock, locked the door, then removed it from the keyhole and placed it next to the stuffed animal acting as the corpse.

However, the question remained.

As I'd confirmed in the hall earlier, there was no keyhole on the outside of the door. That meant there was no way to lock the door from the outside, key or no. Therefore, the culprit must have locked the door from the inside, but that meant there was no way they could have gotten out of the room. The door was locked and couldn't be opened, and the windows were fixed in place, leaving no exits.

It was a locked room. It was the very picture of a locked room.

“Hmm, interesting,” Mitsumura said before snatching the key from my hand. She looked at it and said “Ordinarily, I would question if this key was a fake or not, but in this case, even if it was, it wouldn't change much.”

For a moment, I didn't understand what she meant, but I quickly put it together. In a normal locked room, you could use the trick of leaving a fake key behind at the scene and having the culprit use the real key to lock the door from the outside. But in this locked room, it was different. Since there was no keyhole on the outside of the door, taking the real key out wouldn't change anything. Because a door without a keyhole couldn't be locked with a key. Therefore, there was no reason to take the real key from the scene, and no point to leaving a fake key behind. In that case, it would be natural to take for granted that this key was real.

“But let's check just in case.”

Mitsumura still had the key in her hand as she approached the door. She inserted it into the keyhole and turned it to the right. I heard the sound of the door being unlocked. Mitsumura put her hand on the doorknob. The door slowly opened into the room. As we'd expected, the key left at the crime scene was real.

“This looks like a perfect locked room,” Gentleman said. He closed the door and looked underneath it. “Furthermore, there are no gaps under the door, so there is no way to even collect any traces of the trick from outside after the murder.”

“Every door on Wire Mesh Island is designed to have no gap beneath,” Ms. Hitsujiko added. “Not only in the mansion, but also the doors of the cottages scattered across the island. Therefore, no trick that uses a gap under the door can be used.”

“I see, so that's how it is. Beautiful. As expected from the private island of the great mystery writer Richard Moore.”

The old Gentleman looked strangely happy, but I was already feeling overwhelmed. When I looked around the room, I couldn't even see anything that blocked my line of sight, or in other words, anywhere for the culprit to hide. Therefore, we could discount the possibility that the culprit had been hiding inside the room as well. The room was desolately empty. There wasn't much in the way of furniture, but for some reason there was a rolling chair, the sort that could have its height adjusted.

“It appears a wonderful locked room has appeared before us, ufufu~” said Otomigawara, pleased as punch. “Now, will anyone be able to solve it before sunset? If not, the culprit will receive five points.”

I looked at the clock. It was only three in the afternoon, so there was still plenty of time, but to be honest, it didn't feel nearly long enough to me.

I tried to raise my hand and ask for some sort of hint. But someone else beat me to it. That person was Chiyori Kurokawa, the former judge. Otomigawara tilted her head at her.

“Yes, Ms. Kurokawa, do you have a question?”

Chiyori Kurokawa shook her head. “No, that isn't it.” And then she made her announcement.

“I just wanted to say that I've solved the locked room mystery. That is allowed, right? After all, the Locked Room Trick Game has already begun.”

Everyone looked dumbfounded. Poirotzaka spoke in a panic.

“What? Have you truly solved it already?”

“Of course,” said Chiyori Kurokawa. She kept stroking her short hair with her right hand. “It's not that surprising, is it? It's only natural that a locked room this simple would be solved easily. In fact, I don't understand how you're having trouble with such a third-rate locked room.”

The mystery had been solved... Everyone looked at Chiyori Kurokawa, either questioningly or with hostility.

“Alright then, let's recreate the trick at once.” But the former judge appeared to ignore them all and spoke confidently.”I'll explain how the culprit made this room a locked room.”

We all gasped. Chiyori Kurokawa first approached Mitsumura and and took the key to the room from her. Then she turned her attention to Ms. Hitsujiko.

“There are some things I'll need in order to recreate the trick.”

Ms. Hitsujiko said “Yes, I understand,” and took out her smartphone to take notes. Chiyori Kurokawa gave her shopping list.

“Honestly, I can think of countless ways to lock this room, but for now, I'll use a clothespin, a length of rope, kite string, duct tape, and a remote controlled car.”

For some reason, that made Ms. Hitsujiko's eyes go wide. Then she said “R-Right, I'll prepare it for you right away,” and ran from the room.

After about ten minutes, she returned with all the items requested. Chiyori Kurokawa took them.

“Then let's begin. First, with the door closed, pull the chair with the casters in the room to the door.”

As advertised, Chiyori Kurokawa pulled the chair that had been in the room since we discovered the incident next to the closed door. She inserted the key she'd taken from Mitsumura earlier into the keyhole. She then pinched the flat part of the bow (that's the proper name for the handle of a key. The more you know.) with the clothespin. She wrapped the clothespin with kite string and tied it firmly in place so that it wouldn't easily come off. After confirming it was solid, Chiyori Kurokawa picked up the remote controlled car and pressed one of the rear wheels to the handle of the clothespin, which she once again tied in place with kite string. The key in the keyhole, the clothespin, and the RC car's rear wheel were all connected. The RC car stood up parallel to the door, and the clothespin was tied vertically to the wheel. The clothespin grew out of the tire in an “A” shape.

With that stage of her work complete, Chiyori Kurokawa adjusted the height of the chair, placed the RC car on the backrest, and fixed it in place with duct tape. When she released the remote, it rested on the side of the backrest, completely motionless. It was secured with duct tape, so it didn't seem like it could be moved at all.

Finally, she tied the rope to the wheeled leg of the chair, and tied the other end to the doorknob on the inside of the door.

“Now it's ready,” Chiyori Kurokawa said as she grabbed hold of the remote. “Now, I just use this remote. You all understand what will happen, don't you?”

We all looked at each other. I kind of understood. Right now, the key in the keyhole was being held with a clothespin connected to the rear wheel of the RC car. If you operated the remote in this state – that is to say, if you used the remote to rotate the rear wheel...

“Of course, this will happen.”

Chiyori Kurokawa pressed the joystick to make the RC car go forward. However, the car was fixed in place on the backrest, and the tires weren't touching the ground. So the tires spun without the RC car making an inch of progress. But what did move was the clothespin tied to the tire, which rotated, and the key, held in the clothespin, also rotated...

And with a ka-CHACK, the door was locked. We all exchanged looks of surprises.

“The door is now locked.”

Chiyori Kurokawa announced to the world as she gave the doorknob a twist and tried to pull open the door. But the deadbolt caught and it didn't move an inch. It was perfectly locked.

“Wow, incredible!” Yozuki said, her eyes wide. “This can only be described as a genius trick!”

Yozuki was excited. We all looked at her, wide eyed for a different reason. This was just... sad.

“So, how was this device removed?”

Poirotzaka couldn't stand it anymore and asked. We all nodded. He'd said exactly what we were all thinking.

It was true that the trick Chiyori Kurokawa had just demonstrated could lock the door, even from the outside. However, the objects used in the trick, including the RC car and the clothespin, were still in the room. And now that the door was locked, there was no way to retrieve them. So if this trick had been used, the contraption would have been left inside when we entered the room. In other words, the trick presented by Chiyori Kurokawa was decisively inconsistent with the facts. Of course, it would be a different story if there were some way to erase the evidence of the trick from outside.

However, Chiyori Kurokawa answered our doubts like this:

“Of course, there is a way to retrieve the trick from outside the locked room.” She showed us a smug grin. “But I can't tell you how yet. It's too early.”

The detective's bad habit had appeared.

“It's too early for me to explain that”... I wanted to say that line at least once in my life, but from the point of view of the person being told, it was the most annoying thing in the world.

We all looked resentfully at Chiyori Kurokawa. She ignored us and continued her explanation.

“Next, let's recreate the situation at the moment the body was discovered. But before that, let's go back outside. It will be easier to explain there.”

Chiyori Kurokawa reversed the RC car. The rear wheel of the car rotated in the opposite direction from before, and with another ka-CHACK, the door was unlocked. I see, I think. When the car was moved forward, the door was locked, and when it was reversed, it was unlocked. The RC car's motor wasn't that strong; it could move the key to lock or unlock the door, so once it reached the end of the key's range of motion, it would be stopped, and there was no danger of the clothespin coming loose.

Chiyori Kurokawa slowly opened the door. The rolling chair, connected to the door via the key attached to the RC car attached to the chair, moved with it. Since the chair was tied to the doorknob with the rope, it didn't move away and the key remained in the lock.

Chiyori Kurokawa addressed us as we all stepped out into the hall, keeping her back to the locked room.

“Then, let's recall the situation when we first discovered the incident. What did we do at that time? Um, you...”

Chiyori Kurokawa looked at me, her eyebrows furrowed in confusion. Apparently she couldn't remember my name. ...Even though I'd just introduced myself not long ago.

I had to introduce myself again.

“It's Kuzushiro. Kasumi Kuzushiro.”

“Ah, that's right, Kasumi Kuzushiro.” After Chiyori Kurokawa gave me a cool smile, she asked the same question as before. “Then, Kasumi, I'll ask again. What did we do at that time.”

“Well, um...” I tried to remember. “First, Mr. Poirotzaka checked that the door was locked, right?”

Poirotzaka answered me with an exaggerated nod.

“Ah, that is most definitely true.”

“Then I checked to make sure it was as well,” I said.

At that, Chiyori Kurokawa nodded her head and said “Ah, that's right.”

“At the time, the door was definitely locked. So, let's lock it now.”

After saying so, she pushed the joystick forward. I heard the radio-controlled tires spin from within the room, and the sound of the door being locked. Just to be sure, I tried to open the door. I felt the deadbolt catch. It was definitely locked.

“Now, the situation has been recreated,” Chiyori Kurokawa told us before asking another question. “So, what did we do next? After making sure the door was locked, what did we do?”

“After that, we all went outside the mansion to the window of the room,” Otozaki said. Chiyori Kurokawa nodded.

“That's right. Now, let's reenact what we did at that time. Let's all go out the front door to the window,” she told us.

So we did as we were told and started making our way to the entrance in an orderly line. Then I heard a scolding voice behind me, saying “No.” When I turned around, I saw Chiyori Kurokawa looking at us with dissatisfaction.

“Not like this. At the time, everyone was running. So, please, run the same way. I want our recreation to be as faithful as possible.”

At that, we all looked at each other. Then, like students who'd just been yelled at by our gym teacher, we had no choice but to run. Just like when we'd all gone to see the stuffed animal acting as the corpse earlier, we ran as fast as we could down the hallway and exited out the front door.

Then, suddenly, I stopped. The most important person, Chiyori Kurokawa, hadn't followed us. When I turned back, she appeared from the front door, about a minute behind the rest of us. Even though she looked like she was decently athletic, was she surprisingly slow? We joined up with Chiyori Kurokawa and started running again, eventually arriving at the window of the scene.

“Please look inside the room through the window,” Chiyori Kurokawa said.

We peered into the room through the window that had been broken when we discovered the stuffed animal corpse. Then we all went “What?” What did this mean? We were confused. How had this happened? Why was...

“The RC car is gone.”

I was the one to say it.

When we looked through the window at the door, the RC car that had been there just a moment ago was gone. No, it wasn't just the car. The clothespin, the string and the tape joining it to the chair were also gone. The only thing left was the key, which had been placed on the floor next to the stuffed animal, recreating the scene as we'd initially discovered it.

“How on Earth?” Otozaki asked in confusion. “Where did the RC car go?”

Poirotzaka stared at Chiyori Kurokawa and asked “Did you retrieve it? But how could that be?”

“Did you retrieve it thorough the window?” asked Gentleman.

“No, I didn't,” Chiyori Kurokawa shook her head. “I didn't have time to get to this broken window before you all, and there would have been no point, since the window wasn't broken at the time we found the locked room.”

I could accept that. But if that was the case, then how had Chiyori Kurokawa retrieved the RC car?

I was extremely confused. Judging by the looks on their faces, so was everyone else. Eventually, Otozaki got impatient and said “Come on already!”

“Why don't you just tell us the trick you used?”

At that, Chiyori Kurokawa shrugged and said “Okay.”

“I suppose, if you insist, I can explain it now. But since the trick is so simple, I'm sure you'll be angry with yourself as soon as you know the answer.”

We reentered the room through the broken window. Chiyori Kurokawa picked up the key from the floor and inserted it into the keyhole. Then, after turning the key and opening the door, she led us back into the hallway.

“Allow me to recreate the trick again. Please wait a moment.” Chiyori Kurokawa entered another room in the hallway. She came back with the RC car attached to the rolling chair with duct tape. We were all shocked. The device had been in the locked room at the scene until just a moment ago. When had she had time to move it to another room?

Chiyori Kurokawa ignored our doubts and put the device in the room, and just like before, she inserted the key into the keyhole, clipped it with the clothespin, and secured it all to the RC car with kite string, then she went out in the hall and closed the door, used the remote, and locked the door. The scene was identical to before.

“Now, just like before, I'll retrieve the device from inside the room.”

After Chiyori Kurokawa made her declaration, she looked around at everyone and said this.

“Could you all exit through the front door and face the window from outside again?”

We nodded and ran back down the hall. Immediately, a voice called out “Stop!” from behind us. We all panicked and stopped. When we turned around, we saw Chiyori Kurokawa stroking her short hair.

“Don't move. I'm going to retrieve the RC car now.”

Hearing that made me understand her intentions. I see, so the culprit pretended to be following our group to the entrance, but actually, they stayed behind to retrieve the device.

However, I still didn't know how they'd recovered their device, so I kept a close eye on Chiyori Kurokawa. Then she picked up the remote again and set the car in the room to go backwards. Then I heard the sound of the lock disengaging. It took me a moment to understand, but she'd just unlocked the door. As if to confirm my understanding, Chiyori Kurokawa opened the inward opening door and removed the RC car from where it was taped to the back of the chair, took out a pair of scissors and cut the clothespin free of the key, and crumpled up the key and duct tape and stuffed them in her pocket, grabbed the RC car, left the room, and shut the door behind her. She turned to us, looking proud of herself.

“Now that I've collected the RC car, all I had to do was rush to join you all... And with that, the locked room is complete.”

We stared at Chiyori Kurokawa in silence. Then we stared at each other in confusion.

As Chiyori Kurokawa had said, the RC car had indeed been removed from the scene. But a more important problem had arisen. And that fatal flaw that couldn't be overlooked was...

“Are you mocking me!?” Eventually, Poirotzaka raised his voice as though he couldn't take it any longer. Poirotzaka got right in Chiyori Kurokawa's face, so forcefully he almost touched her chest. “Don't play these sorts of games!” he roared, temper completely lost. “The door is still unlocked!”

It was exactly as Poirotzaka said. It was true that she'd managed to retrieve all the evidence that wasn't found at the scene, but now the door was unlocked. That meant it wasn't a locked room anymore. You can't have a locked room with an unlocked door!

However, Poirotzaka's rage wasn't enough to shake Chiyori Kurokawa's composure.

“And why is that a problem?”

Poirotzaka looked briefly taken aback. Then he got even angrier.

“It's an enormous problem! Because the door to the room wasn't unlocked!”

“Are you sure?”

“Eh?”

“Was that door actually locked?” Chiyori Kurokawa fixed her eyes firmly on Poirotzaka's. “When the incident was first discovered, we gathered in front of this room and confirmed that the door was, indeed, locked. But what about after we broke the window to enter the room? Did we confirm the door was locked then? When we went out the front door to get in through the window, the culprit casually turned back and did what I did earlier. They unlocked the door, retrieved the device, and left the scene, without locking the door. Can you deny the possibility? Can you say with 100% certainty that this door was locked when you entered?”

Poirotzaka was momentarily at a loss for words. However, he quickly exclaimed “Oh, but of course I can, I assure you.”

“Do you recall? After we entered the room, we did endeavor to verify whether the key on the floor was genuine. It was inserted into the keyhole on the inside and rotated. Assuming the door was locked, we turned the key in the direction of 'unlock'. And the key did turn. You heard it yourself, did you not? So, the sound we heard at the time was the proof that the door to the chamber was impenetrable!”

I nodded at Poirotzaka's words. That was right – the door must have been locked at the time.

The door to the scene didn't have a latch on the inside, but a keyhole. That meant there was no way to tell if a closed door was locked or not just by looking. Therefore, I could understand Chiyori Kurokawa's assertion that the door may not have actually been locked at the time. But in reality, that wasn't possible. Because we'd all heard the sound of the lock. So I was pretty sure the door was really locked at that point.

Chiyori Kurokawa nodded and said “Well, I can see how you'd come to that conclusion.” Then she turned to the rest of us.

“But there's a way to solve that problem. A trick to make an unlocked door look locked.”

“A trick...” I said.

“A very simple trick.” Chiyori Kurokawa was grinning. “I'll show you now. Everyone, come inside.”

Chiyori Kurokawa opened the door to the room. After everyone was inside, she followed us in and closed it.

The unlocked door loomed in front of her.

“Right now, this door is unlocked,” said Chiyori Kurokawa. “Even if I insert it into the keyhole and turn it to unlock, it should turn freely, right? But that isn't actually the case. If I do this...”

Chiyori Kurokawa put the key in her hand into the keyhole. Then she twisted it in the direction to unlock it. And...

We heard the sound of the lock.

Everyone's eyes went wide.

“Oh, I see,” Otozaki said quickly. “Didn't you just turn it the wrong way? In other words, you said you were turning it to unlock it, you were actually turning it to lock it.”

“In that case, we would have heard the sound of the lock,” I nodded. “So what we just heard was the sound of the door being locked, not unlocked, which means the door is currently locked.”

Wanting to confirm, I put my hand on the doorknob. I turned it and pulled. The door opened without resistance. I went “Huh?” The door wasn't locked. How was that possible? I'd definitely heard the sound of the lock.

Chiyori Kurokawa pulled her smartphone from her pocket.

She tapped the screen and said “This is the sound you heard.”

Then, from her smartphone, I heard the sound of the lock disengaging. I gasped in understanding.

“So at the moment you turned the key to 'unlock' the door, you also used the smartphone in your pocket to play the sound of the lock?”

Chiyori Kurokawa nodded at me.

“Earlier, when everyone else went to the front door as part of the trick recreation, I stayed behind to retrieve the evidence, right? At that time, I also recorded this. Then I played it back just now.”

Indeed, if you did that, an outside observer would have thought that the unlocked door had just been unlocked. But in reality, it hadn't been locked from the beginning, and they were just pretending to unlock it.

The door we thought was locked was actually unlocked. That was a common pattern in existing locked room tricks, but this one worked because the door actually had been locked. The culprit took advantage of an opportunity to unlock it and retrieve evidence of their trick between when we confirmed it was locked and when we discovered the scene. When we broke through the window and entered the scene, we naturally assumed the door was still locked. We never would have assumed that it had actually been unlocked by the culprit in the few minutes we left the door to go around to the window.

As I stood thinking that, Otozaki looked like he'd realized something. He stared intently at the phone in Chiyori Kurokawa's hand.

“Wait a moment. When the dead stuffed animal was discovered, the culprit played the sound of the lock just like you did, right?” Otozaki put a hand on his chin, tracing his memory. “That means the culprit was the one who inserted the key into the keyhole. Otherwise, there was no way they could have pretended to unlock the door. In other words, the culprit is...”

Everyone's eyes turned to the culprit.

“That's correct,” said Chiyori Kurokawa. “The culprit is you... Shitsuri Mitsumura.”

I was left speechless by Chiyori Kurokawa's theory. Mitsumura was the culprit? That was ridiculous.

Thinking that, I was about to protest on her behalf when an image appeared in my mind. It was Mitsumura with a mop in her hand.

When we'd discovered the incident and ran around to the window of the room, Mitsumura had been holding a mop. Why did she have a mop? That was obvious: of course, it was to break the window. But was that really all there was to it? Maybe not. After listening to Chiyori Kurokawa's reasoning, I could come up with another whydunit.

The locked room trick Chiyori Kurokawa had discussed had one drawback. That was that when everyone else was moving to the room's window, they had to stay behind to retrieve the RC car contraption from the room, which would leave them the only one delayed in arriving at the window. That was clearly unnatural. So what if Mitsumura had used the mop to cover for her unnaturalness? In other words...

She'd been looking for a mop to break the window with.

As a result, she'd arrived late. That was a valid excuse, and at the time I'd thought nothing of it. “Oh, she must have been looking for a mop to break the window” was all I thought.

As the thoughts settled in my head, I turned my gaze on Mitsumura.

“Are you the culprit?”

Mitsumura stared back at me. Then she shrugged.

“Yes, I'm the culprit.”

There was a slight rustle in the air. Before the groups murmurings could dissipate, Otomigawara spoke.

“In this Locked Room Trick Game, it doesn't really matter who the culprit is,” she said. “The only thing that matters is whether or not the detective's theory to the locked room trick is correct or not. So, as to whether Ms. Kurokawa's deduction is correct, please answer yes or no. Oh, and lying isn't acceptable. If she's right, you have to graciously admit defeat.”

Mitsumura smiled bitterly at her statement.

“That wasn't part of the rules.”

“I forgot to add it.”

Otomigawara said that without a hint of shame. Seeing that, Mitsumura have her another smile, then sighed as though she'd come to terms with her defeat.

And she let out the words “Yeah, yeah.”

“All of Ms. Kurokawa's deductions are correct. I used the exact trick she described to lock this room.”

“The winner of the first round is Ms. Kurokawa, who will be awarded three points for solving the locked room. On the other hand, Ms. Mitsumura, whose locked room was solved, will be penalized by being excluded from the Locked Room Trick Game for three days.”

After hearing Mitsumura's confession, our host, Shitsugi, loudly declared the results. Listening to him, I still couldn't believe it. I felt as though my entire worldview had been blow to pieces.

Shitsuri Mitsumura had lost.

Not only that, she'd lost bad.

My eyes swam, but eventually landed on a certain person. A beautiful woman in her late twenties with short hair.

The woman approached Mitsumura. And when she arrived in front of her, she put her mouth next to the girl's ear.

“Have you lost your touch?” said Chiyori Kurokawa. “Or was that on purpose?”

“Well, what do you think?” Mitsumura asked with a shrug.

Seeing her attitude, Chiyori Kurokawa turned and walked away from Mitsumura. Mitsumura stared at her back. Her eyes held a complex mixture of emotions: Pity, hatred, trust, admiration.

 

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