Chapter 3: A Double Locked Room

When Riria heard that Mr. Manei had been killed, her eyes filled with tears. “Tell me you're lying, Miss Fenrir!” she cried as she clung to the older girl. “Unfortunately,” Fenrir replied, “while I can't say for sure without being able to examine the body directly, he's almost certainly dead.”

Everyone in the building was gathered in the lobby. Fenrir had woken them all up. On her recommendation, we decided to leave through the front door and look into Mr. Manei's room through the window. We would look through to see what was inside the room, then break the window to go in.

“Is the door locked?” Yozuki asked as we made our way through the garden. But Fenrir shook her head and gave a vague answer.

“Yes, the door is indeed locked, but there is another problem.”

“Another problem?”

“The lock is not the only reason I cannot open the door. Well, you'll see once we arrive at the scene – which we just have.”

We were right next to the window of Mr. Manei's room. Like Sagurioka's, it was on the first floor of the east building. We looked into the room through the window. Just as Fenrir said, Mr. Manei was lying on the floor.

“Mr. Manei!”

Riria's voice was heartbreaking. But I was more fascinated by the scene inside the room than the man. What the heck? Why were they there?

Why were there dominoes lined up on the floor?

“This is the other reason why we can't open the door,” Fenrir said simply. I looked through the window glass at the dominoes lined up there.

Mr. Manei was lying in the exact center of the room. Surrounding him was a square arrangement of dominoes. The dominoes extended towards the door, continuing right up to the last one, which nearly touched the inward opening door. If the door were opened like this...

“You mean the dominoes would have fallen if you'd opened the door?”

I said that, but that raised an obvious question.

How had the culprit arranged those dominoes? In order to line up dominoes, the culprit had to be inside the room. Judging by the way they went to the door, they must have laid them out with the door closed. So then, how did they escape the room? The moment they opened the door, the door would hit the dominoes, causing them to fall over. But there was no way out unless they opened the door. I muttered to myself a summary of our problem.

“An Incomplete Locked Room.”

A state where the door may as well have been locked – this situation, where the inward opening door was blocked by a domino, perfectly fit the definition given by the Ministry of Justice.

“Anyway, let's break the window and get into the room,” said Dr. Ishikawa. “He might still be alive.”

Although he said that, he didn't sound like he believed it. Looking at the scene through the glass of the window, it was obvious Mr. Manei was dead.

When we broke the window and entered the room, we found that Mr. Manei was already dead. The key to the room was next to the corpse. According to Dr. Ishikawa and Fenrir's autopsies, the estimated time of death was between 3:00 and 4:00 last night. Riria cried the whole time. Yozuki was trying to comfort her.

I looked at the dominoes lined up in the room. I remembered there were dominoes in the hotel lobby alongside Monopoly and other games. Were they the ones the culprit had used?

I moved to the entrance of the room to confirm the placement of the dominoes. With my back to the wall, I followed them with my eyes.

The dominoes were arranged in a square surrounding the corpse. The square was about 2 meters on each side. From the center of the bottom side of the square (as viewed from the door), another 2 meter row extended towards the door. Looking at their arrangement, they made the shape of a square magnifying glass. Or maybe a square frying pan. The handle of the magnifying glass/frying pan reached out to touch the door, and when it was opened, it would hit the handle and send the dominoes falling.

Looking at the door, I saw the hinge was on the left side. That was the view from inside the room. Naturally, it would be on the right if I viewed it from the hallway.

I took hold of the doorknob and gave a pull. I heard the sound of the deadbolt catching. As Fenrir had said, in addition to the blockage of the dominoes, the room was also locked. In other words, this was both an Incomplete and Complete Locked Room.

When I turned my attention back to Mr. Manei's body, I overheard a conversation between Dr. Ishikawa and Fenrir as they performed the autopsy.

“By the way, Miss Fenrir, how did you find the corpse?”

“I was taking a walk in the garden,” Fenrir answered, “There, I happened to see Mr. Manei collapsed in his room. I was shocked. Even if Ms. Shihai's death wasn't a suicide, I thought for sure there would be no more murders.”

Huh. That was exactly what Mitsumura had said.

I turned my attention to Mitsumura, who was standing next to me. She quickly averted her eyes. I kept staring at her until she let out a sigh.

“...Fine. Yes, it's true, I completely misread the situation. The culprit's purpose in making Ms. Shihai's death look like a suicide wasn't to frame her for the crimes. It was to make us think she'd be the final victim so we'd all let our guards down. And as soon as we did, the culprit killed Mr. Manei.”

Whatever the case, the murder drama that had been interrupted had now resumed. The Playing Card Serial Murder Case. That reminded me to ask Dr. Ishikawa.

“Dr. Ishikawa, did you find a playing card?”

“A card? Oh!”

The doctor began to examine the corpse again. Soon, he found it. It appeared to have been placed in the inside pocket of Mr. Manei's jacket. Dr. Ishikawa took it out and showed it to everyone.

“Here it is. This time, it's the two of hearts.”

But to be honest, even though I was the one who'd asked for the card, I was still clueless. I still had no idea what any of the numbers meant.

But Mitsumura, still next to me, muttered something to herself.

“I see, so that's what it means.”

Hearing her say that, I let out a “Huh?” I'm pretty sure everyone else also let out a series of “Huh?”s. Mitsumura shrugged and said to everyone,

“I understand the meaning of the numbers on the cards.”

She ran a hand through her black hair.

“Knox's Ten Commandments.”

Knox's Ten Commandments:

1. The criminal must be mentioned in the early part of the story, but must not be anyone whose thoughts the reader has been allowed to know.
   

2. All supernatural or preternatural agencies are ruled out as a matter of course.

3. Not more than one secret room or passage is allowable.

4. No hitherto undiscovered poisons may be used, nor any appliance which will need a long scientific explanation at the end.

5. No Chinaman must figure in the story.

6. No accident must ever help the detective, nor must he ever have an unaccountable intuition which proves to be right.

7. The detective himself must not commit the crime.

8. The detective is bound to declare any clues which he may discover.

9. The "sidekick" of the detective, the Watson, must not conceal from the reader any thoughts which pass through his mind: his intelligence must be slightly, but very slightly, below that of the average reader.

10. Twins, and doubles generally, must not appear unless we have been duly prepared for them.

“Knox's Ten Commandments?” Yozuki tilted her head.

“A set of rules for mystery novels created by a Golden Age mystery novelist named Ronald A. Knox,” I explained. “Following them isn't a requirement, but they're generally conductive to writing better mysteries. You can think of them like a guideline. The name's a play on the Ten Commandments brought down from Mt. Sinai by Moses.”

Incidentally, Moses's Ten Commandments are 1. You shall have no other gods before Me. 2. You shall have no idols. 3. You shall not take the name of the Lord your God in vain. 4. Keep the Sabbath day holy. 5. Honor your father and your mother. 6. You shall not kill. 7. You shall not commit adultery. 8. You shall not steal. 9. You shall not bear false witness against your neighbor. 10. You shall not covet. (At least, that's what I read on Wikipedia). Knox, who was a Catholic priest in addition to an author, was inspired by them when writing his own Decalogue.

Mitsumura nodded at my explanation.

“Yes, and each of Knox's Ten Commandments have a number. Those numbers match the numbers of the playing cards left at the scenes.”

She looked around at everyone.

“So, let's examine the cases one by one. Let's start with the first murder of the Playing Card Serial Murder Case five years ago. A former detective was murdered, and a six of hearts was left behind at the scene.”

I thought of Knox's Ten Commandments and took out a pen and notepad from my pocket. “Wait a minute,” I said, and wrote down the Ten Commandments so that the rest of the group could understand.

“So, Knox's Ten... What's the sixth commandment?” Yozuki peered at the paper over my shoulder. “No solving cases with accidents or intuition.”

“Yes, that's right,” Mitsumura nodded. “The victim, a former detective, was famous as a great detective when he was active, and apparently he was blessed with incredible luck. He once solved a case by coincidentally stumbling onto the culprit in a bar.”

“You mean to say,” Fenrir said slowly, “that this former detective was able to solve cases by accident or intuition?”

“Yes, in other words, his very existence violated one of Knox's Ten Commandments. And the killer suggested this by leaving a 6 at the scene.”

That made sense to me. Certainly, the first murder seemed to fit the pattern of Knox's Ten.

After confirming that everyone felt the same, Mitsumura continued.

“Okay then, let's move on. The number left at the scene of the second murder was 5, and the victim was Chinese.”

Hearing Mitsumura's words, everyone looked at my written copy of Knox's Ten Commandments.

“This one's easy to understand,” Yozuki said. “Chinese people can't appear.”

The fact that the victim was Chinese matched the fifth commandment of Knox's Ten.

In other words, another match. What next?

“The number left behind at the third murder was 4. The victim was poisoned with a previously undiscovered species of poisonous mushroom.”

“Well, what's Knox's fourth commandment?” Dr. Ishikawa took over the explanation. “No undiscovered poisons may be used, and no machines that would require a difficult scientific explanation. A new species of poisonous mushroom could be called an 'undiscovered poison'. I think this also applies.”

“Yes, now we know that the three incidents that happened five years ago all correspond to Knox's Ten Commandments. So, what about the four incidents that have occurred here at the House of Snow?”

When I heard Mitsumura's words, I searched my memories. What were the numbers on the cards left at each of the scenes? I added that information to the paper I'd written Knox's Decalogue on.

First Murder – Victim: Kanzaki – Card: Ace

Second Murder – Victim: Shihai – Card: 10

Third Murder – Victim: Sagurioka – Card: 7

Fourth Murder – Victim: Manei – Card: 2

“The easiest one to understand is Mr. Sagurioka, the detective,” Yozuki said. “He alludes to the seventh commandment, the detective can't be the culprit.”

So Sagurioka was a match. What about the remaining three?

“Shihai had a younger twin sister,” Miss Meirozaka said, “so she also matches with Knox's tenth, the one about not allowing twins the reader hasn't met.”

I remembered what Miss Meirozaka had told me on the first day. She'd said that Ms. Shihai's twin sister was a farmer who sent the hotel fresh vegetables.

So Ms. Shihai was also a match. And then there were two.

“Mr. Manei...” Riria rubbed her eyes, which were swollen from crying. “He used to be a fortune teller. He used those tarot cards to tell Kuzushiro's fortune, right? Does that fit Knox's second commandment about using supernatural abilities?”

I see, I think. But Yozuki had her doubts.

“What does 'supernatural' mean here? Like psychic powers and stuff?”

“Things like fortune telling and divination,” Mitsumura explained. “In the early days of the mystery genre, there were many novels that used methods like those to expose the culprit.”

With that, the match was made. In that case, the only one left was... Kanzaki.

“Knox's first commandment is 'The criminal must be mentioned in the early part of the story',” Yozuki said, arching one well-shaped eyebrow. “I don't get it. First off, what does 'mentioned in the early part of the story' mean?”

It's not like we were characters in a mystery novel or anything.

However, Fenrir, who'd been deep in though, softly spoke to herself. “I see, so that's what it means.” When we all turned to look at her, she spoke calmly.

“The first of Knox's Ten Commandments may be summarized as 'Someone who has not appeared since the beginning of the story may not be the culprit'. And Mr. Kanzaki was the last person to arrive at the House of Snow. If we were to view the events of this series of murders as a story, then Mr. Kanzaki would be someone who 'wasn't there from the beginning'.”

Everyone gasped. That was... well, frankly, it was completely insane, but it made sense.

Now, all seven murders – the three that were committed five years ago, and the four that took place here in this mansion – all conformed to the pattern of Knox's Ten Commandments.

“This is the true meaning of the cards left behind at the scenes,” Mitsumura said. Then, she turned to look at Miss Meirozaka. “So, based on what we've deduced so far, there's something I'd like to ask you, Miss Meirozaka.”

Miss Meirozaka tilted her head. Mitsumura asked her question.

“Are there any secret passages or hidden rooms in the House of Snow?”

Everyone's gazes were naturally drawn to the paper where I'd written Knox's Ten Commandments. The third commandment...

“Not more than one secret room or passage is allowable.”

 

That suggested it was allowable to use one secret passage. That was probably why Mitsumura had asked, but I wanted to blurt out “Just what kind of stupid question is that?” This wasn't a mystery novel, so there was no way a building with something like that could exist.

As expected, Miss Meirozaka answered her:

“Yeah, there is.”

...Wait, what?

Miss Meirozaka led us to the dining hall, where she picked up the remote that controlled the heating, placed her thumb to its back, and pressed hard. The plastic back of the remote slid over to reveal another button. We all made various “wow” noises.

“This remote opens the hidden room,” Miss Meirozaka said, pointing at the south wall of the dining hall. “The entrance is over there.”

What she was pointing at was a cupboard set against the wall. It was the one next to where Ms. Shihai's corpse had been. The cupboard slid about a meter over, revealing a space equal in width in the wall, concealing a staircase to the basement. We all went “wow” again.

“There's a hidden room at the bottom of these stairs.”

Miss Meirozaka said that and went on down. A sensor responded by turning on the lights automatically. We arrived at the hidden room after about 30 seconds.

It was dimly lit, with a high ceiling. With our eyes that were widened at the sight of a hidden room, something that should have only existed in a mystery novel, we immediately saw something in the center of the room. Something in the shape of a human. No, that was...

“A corpse?”

When I said the words, Yozuki's shoulders started trembling. I immediately ran towards the thing that looked like a corpse. Dr. Ishikawa and Fenrir came with me. The three of us looked down at it.

“He's dead,” Dr. Ishikawa said leisurely.

“He'd dead!” Fenrir said happily.

Those two were beyond help... I started down at the corpse at my feet. The figure was a man wearing a suit, and no matter how you looked at it, he was dead. Or rather, he was mummified.

I asked Dr. Ishikawa,

“Do you know the estimated time of death?”

“Don't be unreasonable,” Dr. Ishikawa said with a dissonant smile. “I'm a doctor, not a medical examiner. All I know is it's been a long time.”

Was that it, then? As I stood thinking that, Fenrir, who'd been investigating the corpse, spoke up.

“The estimated time of death is four months ago.”

Dr. Ishikawa's eyes went wide.

“You can tell? That's incredible.”

“No, my autopsy would be useless,” Fenrir said as she showed us something that looked like a pass case. “I found this in the corpse's pocket.”

We took the pass case and checked inside. Inside we found a driver's license. Apparently the man's name was Shinkawa. He was 30 years old. After staring at the driver's license for a while, Dr. Ishikawa spoke up.

“How does this tell you the time of death?” he asked Fenrir. “His driver's license hasn't expired yet, so I don't think that can tell you when he died.”

“No, this man is just an acquaintance of mine.”

“He is?” I asked in surprise.

“Yes, Mr. Shinkawa is also a member of Tower of Dawn, just like myself and Mr. Kanzaki. He has been missing for about four months, so I figured that is likely around the time he was killed.”

Dr. Ishikawa and I both nodded in understanding. That would be the natural conclusion to draw.

Everyone who'd been observing the corpse from a distance chose that moment to come closer. Mitsumura, who was among them, asked me a question.

“Was there a playing card?”

“A card? Ah.”

I turned back to the corpse and, timidly, went through its pockets. The card was in his pants pocket. A three of hearts, matching the third of Knox's Ten Commandments, “Not more than one secret room or passage is allowable”.

“But why is the culprit using Knox's Ten Commandments?”

When Dr. Ishikawa expressed his doubts, there wasn't much Mitsumura could say.

“Unfortunately, I don't know the answer to the whydunit yet. I feel like it could be extremely revealing, but I also feel the culprit might just be having fun. I can't say anything at this stage.”

Mitsumura turned to look at Miss Meirozaka. As though changing the subject, she said “I'd like to ask you something.”

“Other than yourself, Miss Meirozaka, who else knew about this hidden room?”

Miss Meirozaka slightly leaned to the side and thought for a moment. Then she answered.

“It was basically just me and Shihai. However, I hear that Byakuya Yukishiro often boasted about this hidden room to his guests, so actually, the number of people who know about it might be quite high. If we include the number of people who theoretically could have known about it, I'd have to say 'I dunno'.”

I see, I think. In other words, anyone currently in the room with us could have known about it ahead of time and just not mentioned it.

“By the way, why did you keep quiet about this room until now?”

“Because I didn't think it mattered,” Miss Meirozaka said. “I had no idea there was a dead body down here.”

“But when Ms. Shihai's body was found, the dining hall was a locked room,” I interjected. “In that case, shouldn't we have considered the possibility that the culprit was hiding in his hidden room connected to the dining hall?”

For some reason, Mitsumura and Miss Meirozaka both shrugged at the same time.

“No, Kuzushiro, we shouldn't have. After all, the possibility that the culprit was hiding inside the locked room had already been ruled out.”

“That's right, because the possibility of an outside culprit had already been denied,” Miss Meirozaka said.

“Yes, when we found Ms. Shihai's body, we were all gathered together. Since the culprit is an insider, how could they have been inside this hidden room? It's impossible. No one was missing, so we didn't need to consider the possibility that someone was hiding in this room.”

They shot my idea down so quickly. It was kind of upsetting. Mitsumura ignored me and kept talking to Miss Meirozaka. “By the way, I have one more question.”

“Are there any other hidden passages or secret rooms other than this one?”

Miss Meirozaka shook her head.

“No, nothing else.”

“Do you have any basis for asserting that?”

“Before we opened this place as a hotel, we hired an appraiser.”

Mitsumura's eyes widened slightly.

“A locked room appraiser?”

Miss Meirozaka nodded.

Locked room appraisal companies are companies that specialize in investigating mansions and other buildings to find secret passages. When a locked room murder occurs, the police call them in to thoroughly investigate the building. Because they use ultrasound and x-rays, their accuracy is almost perfect. When the police investigate a locked room murder, standard practice is to first have a locked room appraiser confirm or deny the possibility of a hidden passageway and rule out the possibility that the culprit used a hidden passage to escape the locked room.

However, for a private building that hadn't been the scene of a crime to hire a locked room appraisal company was rare. Miss Meirozaka explained that.

“This was once a mystery writer's house, after all. If there were some trick we didn't know about, it'd cause problems for the guests.”

We accepted that explanation. “Then there's one more thing I'm curious about,” said Mitsumura.

“Who brought this corpse into this room, and when?”

Miss Meirozaka raised her hand slightly and said “Oh, I can explain that.”

“About two months ago, a suspicious guest came here. They were wearing bulky clothes and sunglasses, and I couldn't tell if they were a man or a woman. They were somewhere between 170 and 180 centimeters tall. They were probably using platform shoes or something to disguise their real height. They also had a big trunk.”

“So that guest brought the corpse into this hidden room?”

“I think it's pretty likely. Besides, Shihai and I barely ever use this room. I think the odds of it being found were low, even if they left it here for two months.”

Mitsumura started thinking. I imitated her and placed my hand on my chin, but then I noticed something lying a bit away from the corpse. I went over and picked it up.

“A silver coin?”

It was a silver coin about the size of a 500 yen piece. However, it didn't appear to be any actual currency. The only thing stamped on it was “L”, one on the front and one on the back.

“L?”

What is this? When I tilted my head at it, Mitsumura, who was looking over my shoulder, started in surprise.

“Kuzushiro, what's that coin?”

“Do you recognize it?”

“I'm not sure...”

Mitsumura paused in thought again. It looked like she was sorting something out in her head. What was going on? Was this coin really that dangerous?

Then Fenrir came over and said something.

“Do you know what a locked room agent is?”

Yozuki and I looked at each other. Yozuki shook her head. But I'd heard of them.

“They're what you'd call hitmen, right? They kill people on request, and always in locked rooms.”

“Not quite,” Fenrir said. “Some locked room agents do perform murders themselves, while others simply come up with locked room tricks for their clients. And that silver coin marked with an 'L' is the calling card of one particular locked room agent. He – or is it she? – is one of those who don't just provide their clients with tricks, but also perform the murders themselves. And since this silver coin was found at the scene, there is a strong possibility that the murders taking place here at the House of Snow are the work of that locked room agent.”

Fenrir elegantly stroked her silver hair as she spoke.

“They are said to be the most dangerous of all the locked room agents. In the three years since the beginning of the Japanese locked room boom, they have already killed more than fifty people. The police and their peers in the murder industry call them...”

Her silver bell voice echoed in the room.

“The Locked Room User.”

After we emerged from the hidden room, I explained our progress in the investigation to the others. To be precise, I told them that we already knew the solution to Sagurioka's locked room. But nobody seemed to care that much. Their reaction was understandable – Mr. Manei's corpse had just been found in an all new locked room, plus we'd found evidence of the Locked Room User's involvement. In order to escape the situation we found ourselves in, just solving one locked room wasn't enough.

So, in order to resolve everything, I decided to head to the east building with the dominoes I'd gotten from the lobby. Of course, my goal was to uncover the locked room trick used in Mr. Manei's murder. However, if I carried out the trick in Mr. Manei's room, the original domino setup at the scene would be destroyed. Therefore, I decided to copy the trick in the room next to it. The layout of the rooms was the same, so there shouldn't have been any problems.

And surprisingly enough, Mitsumura came with me. Even though she'd been so reluctant to help solve the case up until now, she'd suddenly gotten motivated.

When I asked about that, Mitsumura frowned and said “Given my position, I didn't want to stick out too much.” She raised an eyebrow. “But now I've already made such a big show of my deductions that it doesn't matter anymore. In that case, I'd like to just catch the culprit and get a good night's sleep. I haven't been able to sleep well the past few days. I only got six hours last night.”

I think that's plenty, though...

When we arrived at the room, I lined up the dominoes, just like at the crime scene. Mitsumura watched from the side.

After I'd lined up enough dominoes, I left the room. I asked Mitsumura to wait inside. I took out a wire I'd borrowed from Miss Meirozaka. I opened the door a crack and inserted the wire, which I'd bent into the shape of an L, through the gap. I tried using the wire to bring the dominoes closer to the door.

The doors of the rooms on the first floor of the east building were all like Sagurioka's, with no gaps under them. When the door was closed, there wasn't even enough room to fit a thread through. So the only way to move a domino from the outside was to open the door a crack and fit the wire through.

After about ten minutes of work, I wiped the sweat from my forehead and called out to Mitsumura inside the room.

“How does it look? Are the dominoes lined up properly?”

If I opened the door, the dominoes would all fall down, so I couldn't check from out in the hallway. Mitsumura's voice came through the door.

“Unfortunately, no. The mess is quite terrible.”

“Really?”

“Yes, most of the dominoes have fallen. I don't think this method will work.”

This is ridiculous, what were the past ten minutes of work for?

I opened the door and entered the room. Pushed by the inward opening door, the dominoes that were still standing all collapsed.

After thinking for a spell, I decided to go back to the scene. Mitsumura followed behind. Returning from the east building to the lobby, I went out into the garden. I went around to the window of Mr. Manei's room and climbed through. Even though it was just the next room, it was a long walk. How bothersome.

I followed the dominoes lined up in the room with my eyes. The dominoes circled (well, squared) the body and lead to the door.. And they stopped right in front of the door. There was about an inch between the first domino and the door. That meant that opening the door even a little would knock the dominoes down. In that case, my idea of opening the door a crack and moving them with wire would be completely impossible.

Then I noticed something.

“The flooring is different than in the other rooms.”

“Yes,” Mitsumura agreed. “Unlike the other rooms, it looks quite rough.”

The floor of the other rooms was smooth and polished, but the floor in here was rough. It didn't appear to have been waxed, either. It was damp to the touch. Somehow, it reminded me of an abandoned house during the rainy season.

“Maybe the flooring in the other rooms was renovated at some point,” Mitsumura said, “And for some reason, only this room was not.”

“Why would that have happened?”

“How could I possibly know something like that?” Mitsumura said with a shrug.

Afterwards, I stared at the dominoes on the floor for a while, but I realized that was getting me nowhere, so I decided to focus on something else. After snapping a picture of the dominoes with my smartphone, I carefully removed the ones near the door. That may not have been the right thing to do from the perspective of preserving the scene, but it was the only way we could open the door.

I turned the inner lock and opened the door. Yes, there was another major problem with this crime scene. Not only was the door blocked by dominoes, but it was also locked. Again, this was both an Incomplete and Complete Locked Room.

“It's a kind of double locked room.”

That was what Mitsumura said.

A double locked room usually refers to a situation where there are two doors between the body and the first discoverers, and both of them are locked. I wasn't sure if a situation like this, where a single door was blocked in two different ways, really qualified as a double locked room.

By the way, I said earlier that the only key to the room was found next to the corpse, and we already confirmed it was the real key. We physically inserted it into the keyhole and confirmed that it locked and unlocked the door. In addition, there was no master key to the east building, so it was pretty unlikely one was used to lock this door.

In that case, how did the culprit create the locked room? I investigated the door for a while, and found something important.

“Mitsumura,” I said to her, thrilled. “The deadbolt!”

“The deadbolt?”

“Hasn't it been cut partway?”

I pointed to the deadbolt sticking out of the open door. At first glance, it looked normal, but looking closely, there were traces that it had been cut short in the middle and repaired with adhesive. Could it be a clue?

“Hmm, I see,” said Mitsumura, intrigued. “I wonder if the culprit was the one to cut it?”

“I can't think of any other possibilities.”

The culprit must have used some tool or another to cut the bolt during the night. It may have made a loud noise, but the victim, Mr. Manei, was the only person left staying in the east building. Everyone else, including Miss Meirozaka, was staying in the west building. And there was no way a sound would carry all the way to the west building from here.

When I explained all that, Mitsumura agreed, saying “Yes, you're probably right.” Then she said “Wait a minute,” and hurried out of the room. Eventually, she returned with a pair of pliers. She pinched them on the deadbolt and gripped hard with a twisting motion. Eventually, the glued deadbolt was levered off. I gasped.

When the door was locked, the reason it couldn't be opened was because the bolt got caught in the holder in the door frame. So what if there was no bolt? That would mean that even if the door was locked, there was nothing stopping the door from opening and closing.

The culprit must have cut the bolt short of the holder. Then, they set it to the locked position and shut the door. By applying adhesive to the cut end of the deadbolt in advance, the deadbolt could be glued when the door was closed, making it appear that the bolt had never been cut.

The mystery of the locked room had been solved. As if to confirm my reasoning, I turned the knob and tried to shut the door. But something unexpected happened. The door didn't close. When I looked, I saw about 5 mm of bolt sticking out of the door. That 5 mm of deadbolt hit the door frame and stopped the door from closing. I put all my weight on the door, trying to push it in. Of course, it didn't work. Without clearance between the door and the frame, even 5 mm was enough to cause problems. Why did these things keep happening to me?

The deadbolt had indeed been cut short. But it hadn't been cut short enough. The door still locked and unlocked normally.

“That's a shame, Kuzushiro,” Mitsumura said sympathetically before placing a hand on the lock. She turned it and retracted the exposed deadbolt. The sound of the thumb turn's spring echoed through the hallway. Then she shut the door and turned it again. Then she pulled the knob. I heard the sound of the deadbolt catch on the door. Seriously, just one win, that's all I ask...

“So even if the deadbolt was shortened, it won't have any effect on whether the door can be locked?”

Mitsumura shrugged a bit.

We spent the next 30 minutes trying to figure out the mystery of the locked room, but Mitsumura looked like she was getting tired, so I decided to give up for now. When we returned to meet the others in the lobby, for some reason there was a commotion going on. As I was standing there, wondering what was up, Yozuki came up to me.

“Look, there,” she said, pointing to a table. There was a familiar figure sitting there. “Mr. Yashiro's back.”

At the table was an exhausted looking man in tattered clothes. He was around 40. Mitsumura tilted her head.

“Who is that?”

I think she was serious.

“That's Mr. Yashiro, the president of a trading company. He was a guest here, remember?”

“Oh, there was someone like that, wasn't there?” she said, looking a little embarrassed. Apparently, she'd really forgotten. “...But he went down the mountain, didn't he? On the second day, after Mr. Kanzaki's body was discovered.”

That was certainly the case. Since he'd tried to force his way down the snowy mountain, he must have gotten lost. To be honest, I thought he'd died.

“He just came back,” Yozuki said. “And now Dr. Ishikawa and Miss Meirozaka are questioning him.”

Dr. Ishikawa and Miss Meirozaka were indeed sitting across from him at the table, although “questioning” may have been a bit harsh. I could hear them from where I stood. It seemed Yashiro had gone into the forest, but gotten lost immediately. After wandering in the mountains for two days, he'd miraculously found his way back to the mansion.

“Why did you try to go down the mountain like that? Even a child would realize you'd get lost.”

Miss Meirozaka flatly said something so harsh. Yashiro responded in an exhausted voice.

“I was afraid of being killed. I know someone's targeting me.”

“Why would someone want to kill you?”

Dr. Ishikawa asked. Yashiro told a story.

Apparently, he'd committed investment fraud in the past. He'd made a lot of money, but he'd also made many enemies.

“I never regretted my decision until I arrived at this mansion,” he said. “In fact, I'd almost managed to forget it had ever happened. But when someone died here in this mansion, and the bridge burned down... I became scared that maybe the culprit had burned the bridge so they could kill me.”

Confessing his guilt appeared to make him somewhat refreshed. He looked like he was approaching a state of enlightenment. He even spoke apologetically when talking to Miss Meirozaka.

“I'm sorry, but can I ask you for something to eat? I haven't eaten in a while.”

“Yes, if you're okay with something simple, I can get it right away.”

Yashiro and Miss Meirozaka both got out of their seats and headed towards the dining hall. Mitsumura called out to Miss Meirozaka. They spoke for a while in low voices. When she returned, I asked Mitsumura about it.

“What were you talking about?”

“The security camera on the gate,” she said. “I wanted to know if Mr. Yashiro really had come back when he said he did, and not sooner.”

I see, I think. She wanted to see if it was possible he was the culprit. If Yashiro had been hiding inside the mansion since he “left”, that would definitely make him a suspect.

“So, how about it?” I asked.

“Mr. Yashiro is clean,” she replied. “Miss Meirozaka appears to have had the same thought, so she checked the security camera immediately upon his return. He really did only come back just now. In other words, it's impossible he could have been the culprit.”

After Mitsumura said that, she turned her attention to the water bottle on the front desk of the lobby. “What's this?” she asked, picking it up. “Oh, that,” Yozuki said.

“Miss Meirozaka just found it in the hotel storeroom. She was wondering who it belonged to, since it isn't a hotel item.”

“Hmm...” Mitsumura looked at the water bottle. It was a pure white bottle with a capacity of about three liters. I felt like the lid was tighter than a regular water bottle's.

When I picked it up myself, it was surprisingly heavy. It definitely wasn't a normal water bottle.

As I sat in the lobby, thinking about locked room tricks, Mitsumura was working on something with cardboard and a pair of scissors. When I asked “What are you making?”, she replied “Not telling.” She was being secretive.

“More importantly, I really need to clear my head a bit, so will you at please talk to me?”

She said that as she moved the scissors. I looked at the secretive girl with a blank expression, but curtly nodded. I also needed to clear my head.

“What do you want to talk about.”

“Regarding the circumstances when we found Ms. Shihai's body,” Mitsumura said, “something about them bothers me. But I don't know what it means.”

“What's on your mind?” Personally, I was more interested in what it was, but... “Alright. Where do you want to start?”

“Let's look back on everything that's happened since yesterday morning in chronological order. Kuzushiro, you arrived in the lobby around 5:00 A.M., right? First, I need to know what happened around that time. Can you tell me?”

“Ah,” I nodded. “When I went to the lobby at 5:00 A.M., I saw Yozuki, Riria, and Mr. Manei already there. We started talking about Mr. Manei's tarot readings.”

I explained everything I'd seen and heard until we discovered Ms. Shihai's body. We also confirmed with each other what had happened before Sagurioka's body was discovered. I did most of the talking, and Mitsumura listened and did her mysterious work, but eventually, at a certain point in my story, she said “Stop.”

Scissors still in hand, she put a hand on her chin and silently mouthed something.

“I see, so that's what it meant.”

“What? What do you see?”

“Could you please shut up for a moment? I need to think.”

Something terrible had been said to me. I obediently shut up. It was a sad time all around.

Eventually, she took her hand off her chin. Then she looked at me.

“I'd like to confirm one thing. Did anyone approach the window when Ms. Shihai's body was discovered?”

“By window, do you mean the one on the north side of the dining hall?”

The entire north wall of the dining hall was a single large window to let in the light. However, the place where Ms. Shihai's body had been placed was far from there, and if anyone had approached that window, I definitely would have noticed.

So I could answer:

“I don't think anybody went near it.”

“Then, what about when you returned to the dining hall after discovering Mr. Sagurioka's body?”

“No, nobody approached... no, wait.” I remembered. Come to think of it, at that time, Yozuki had approached the north window. It was when she went to grab the remote control to turn down the heat.

“So, nobody approached the north window before Yozuki.”

After saying that, Mitsumura put down her scissors and looked at me.

“I finally figured it out. That's all.”

My eyes shot open.

“What do you understand? The locked room? Or the culprit's identity?”

“Both,” she said. She stroked her long black hair. “The Broad Locked Room where Ms. Shihai was killed, the double locked room where Mr. Manei was killed – and the true identity of the Locked Room User who killed them. I know everything.”

Mitsumura made the declaration.

“The case has been solved.”

 

 

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