Chapter 6: The Seventh Locked Room

“What is this?”

When I saw the headless corpse lying there, I spoke in bewilderment. Although the missing head was nowhere to be found, judging by the body's physique and its clothing, it was safe to assume it was Otomigawara. Mitsumura stared at it wide-eyed as though at a loss for words, then put a hand to her mouth.

“What does this mean?” Yozuki asked. “Does this mean Ms. Otomigawara wasn't the culprit?”

“I don't think that's the case,” said Mitsumura.

“B-But she's dead!”

“Yes, yes she is,” Mitsumura said, stroking her black hair. “I don't think I can argue with that...”

There was a heavy silence.

“I'm going to go look for Dr. Iori.”

After saying that, Ms. Hitsujiko left the study of the Tower of Heaven. When silence returned, I looked around the study again.

The room was circular, about ten meters in diameter, and was a study in name only, with very few bookshelves. The room had no walls, instead being surrounded by floor to ceiling windows, all of which were now open, letting in the early summer's evening air. Each window stood about 10 meters high, giving the room a pleasantly open feeling. When there wasn't a headless corpse, I mean.

The room's furniture consisted of a couch, a table, and two waist-high bookshelves. Plus a full length mirror on casters. On the table was a glass vase full of dandelions and a toy rabbit in a dress. There were five dandelions, apparently picked by Otomigawara herself, and none of them had lost so much as a single fluffy seed to the wind.

The toy rabbit's head had been severed with a knife, and there were scars left on the table by that same knife. A miniature knife had been placed next to the rabbit. It appeared that knife had been used to sever the head, and the words “The Living Locked Room Library” were written in pure gold on the handle.

It was the same as the toy rabbits and knives left at the other crime scenes thus far, so it was definitely part of the serial killing.

In that case, Otomigawara wasn't the culprit after all. One of us, someone still alive, was the Living Locked Room Library, and they'd carried out another crime as though mocking us.

I felt helpless.

Mitsumura's reasoning was wrong. We'd lost.

The door to the study wasn't locked, so the crime scene this time didn't appear to be a locked room. That made me uncomfortable. Why had the Living Locked Room Library decided not to commit a locked room only in this one case?

As I was thinking that, Ms. Hitsujiko finally came back with Dr. Iori. She looked pale. She'd probably already been told that Otomigawara had been killed.

But when she saw the body for herself, she screamed “Oh my God!”

“T-The culprit is going to kill us all!”

Dr. Iori covered her mouth like she was holding back nausea. Ms. Hitsujiko looked at her apologetically.

“I'm sorry, Dr. Iori, but we need you to perform an autopsy...”

Dr. Iori's eyes widened in desperation. Then she moved away from Ms. Hitsujiko and said in her most threatening voice “I-I don't want to.”

“What? Why not?” asked Ms. Hitsujiko, confused.

“Why? B-Because! It's obvious!” Dr. Iori shouted in a strained voice. 

Then she glared at everyone.

“The person who killed Ms. Otomigawara and everyone else is one of you, isn't it? That means now is no time to be performing autopsies in a place like this! It's not! It's not!”

Dr. Iori reached into her pocket with shaking hands and pulled out a fruit knife. She gripped it tightly and pointed it at us.

“Dr. Iori,” Ms. Chiyori pleaded, “calm down. Nothing will be accomplished by baseless suspicion.”

“Shut up!”

Dr. Iori threw her knife at Ms. Chiyori. It didn't actually reach her, clattering to a stop at her feet, but Ms. Chiyori flinched and she quickly ducked behind my back. Sure, use me as a human shield, why not?

Dr. Iori reached back into her pocket and pulled out another knife, and shrieked “A-Anyway!”

“Please, don't bother me anymore! I'll protect myself! I-I'm not staying with a murderer in a place like this!”

With that, Dr. Iori ran out of the study. Mitsumura watched her go, then spoke.

“Well, if that's how she feels.”

That girl was entirely too calm.

“Weren't you scared?” I asked her.

“Scared? Why?”

Mitsumura looked shocked. I was the one who should have been shocked, though.

“Didn't you think there was a possibility you could have been killed?”

“No, not at all,” Mitsumura said. “Because I've never done anything to make someone hate me.”

I wondered who had just said that. Because that statement made no sense coming from Shitsuri Mitsumura.

Setting that aside for a moment, Mitsumura went on to say “Besides...” and looked thoughtful. But eventually, she shook her head.

“Well, whatever. We'll talk more after I've had a chance to gather my thoughts.”

She said that and turned to Ms. Chiyori. And she made a suggestion.

“Since Dr. Iori has left us, we probably have to give up on determining a time of death. But if it's just the cause of death, we can probably find that on our own.”

Ms. Chiyori's eyebrows shot up.

“You want me to examine the body?”

“You're used to seeing dead bodies, aren't you? You are a former judge.”

“Just what do you think a judge is?” Ms. Chiyori protested. “I've seen photos of murder victims in court records, but the first time I ever saw one in person was when I came to this island. Do you think I'll be of any use?”

Mitsumura shrugged and said “It can't be helped, can it?”

“There's no one else here who can examine a corpse. And just having seen photos is enough. I think the average person goes their entire life without ever seeing even a photo of a murdered body.

Mitsumura and Ms. Chiyori approached Otomigawara's corpse for the autopsy. To my own surprise, I followed them.

Otomigawara's corpse was lying dead center of the room. The head, which we'd thought had been cut off, actually wasn't; it looked more like it had been torn off by a powerful force.

There was no doubt that was the cause of death...

“How the hell is this even possible?” Ms. Chiyori asked in total shock.

“Not with any amount of human strength,” Mitsumura mused. “Perhaps the culprit was a gorilla, or maybe a creature like the yeti.”

“Huh? Yeti?”

Yozuki reacted to her words. Yozuki liked UMA, and especially the yeti. She'd even once dragged me out to a mansion in Saitama to look for a yeti.

“But even ignoring the mystery of how the head was removed, looking at the circumstances of the crime, it would still be impossible for a human culprit.”

Ms. Hitsujiko said that softly. Mitsumura, who seemed curious about that, asked “What do you mean?”

“The truth is... there's only one entrance to the Tower of Heaven,” said Ms. Hitsujiko. “But the only entrance is monitored by a surveillance camera. So if the culprit doesn't appear in the camera footage, than the only possibility is that the culprit entered the room another way. And the only other way in is...”

I followed Ms. Hitsujiko's line of sight. I could immediately guess what that other route was.

“The window?”

I muttered that as I looked out the windows again.

The circular room had no walls, only retractable glass windows. The windows rolled down like those of a sports car, so when the windows were open, as they were right now, there was no glass visible in the room, just a series of window frames like pillars encircling the edge of the room.

I approached a window and immediately felt a latent fear. Since there were no walls, it was no different than standing on the edge of the roof at the school building. There was no railing, so I held the edge of the window frame as I peered down. There were no rooms in the Tower of Heaven other than the study, so there were no windows, balconies, or any irregularities beneath us, just a single smooth tower surface continuing all the way to the ground 40 meters below us. There was no way a person could climb this wall.

But it might have been possible to break in my hooking a rope to the window frame and climbing. That's what I thought...

“No, that's impossible.” But Ms. Hitsujiko rejected my idea. “There are crime prevention sensors embedded along the outer wall of the Tower of Heaven at a height of 20 meters, completely encircling the tower. If someone tried to pass that area, they would be caught by the sensors and an alarm would sound. The sensor's range is quite far, and they absolutely wouldn't miss the presence of the culprit climbing a rope.”

So, there was no way that the culprit had used a rope to climb to the window. And there was also no possibility that a non-human creature, like, say, a yeti, could use their strong, muscular arms to scale the wall, either. Since there were sensors on the outer wall, the yeti would have been caught.

“So, Mothman?” said Yozuki, who had suddenly appeared next to me by the window. “Looks like we have no choice but to conclude that the culprit is Mothman.”

What do you mean, “we have no choice”? She was acting like a great detective, but her deductions were absurd. In the first place, what's “Mothman”? It was probably another UMA.

“Mothman is a moth-human monster from America.”

I knew it. So, it was a moth monster. In that case, it would be able to fly up to the window by flapping its wings.

But I had to ask.

“By the way, why would an American monster be in Japan?”

“Long ago, Japan and America were connected...”

Yozuki started a smug lecture. I felt a headache coming on...

Just to be sure, I decided to check the rest of the study's windows. No matter which one I looked out, I saw a similar sight, but beyond the southernmost window was a sheer cliff over a several meter drop to the sea quite close to the window. Beyond it lay the fence of Wire Mesh Island. The distance between the window and the fence was only about three meters. However, the study of the Tower of Heaven stood about ten meters above the top of the fence, and besides which, the fence was equipped with a motion sensor, so if anyone tried to climb it, an alarm would go off. There was no way anyone got to the Tower of Heaven by climbing the fence.

So, what about the truck-mounted crane? That had already been used in two other tricks now. However, even if you extended the crane as high as it would go, it wasn't tall enough to reach the window, and the Tower of Heaven was surrounded by a waist-high fence that made it impossible for a vehicle to approach. Therefore, it seemed unlikely that the truck-mounted crane was used.

Afterwards, we all returned to the mansion to check the surveillance camera at the entrance to the Tower of Heaven. As expected, nobody appeared on it.

“In other words, the Tower of Heaven was, in a way, a locked room.”

Mitsumura called it like it was. It was true that with the entrance monitored by a camera, there was no way to use it to go to the study, and we'd already confirmed it was also impossible to enter via a window. In short, as Mitsumura said, the Tower of Heaven was a locked room. And honestly, that was understandable. Since this was a series of locked room murders, it would be stranger if this latest one wasn't in a locked room.

As I thought that, I told Ms. Hitsujiko something that had been bothering me for a while now.

“There sure are a lot of security cameras on this island.”

There was a surveillance camera in front of the “prison” that Mitsumura had been in, one in front of the room where the sixth key to the portable safe had been kept, and now the one on the door to the Tower of Heaven. Just how many cameras were on this island, anyway

Surprisingly, Ms. Hitsujiko said “No, there aren't that many.”

“Aside from the ones on top of the fence surrounding Wire Mesh Island and the one at the gate, there are only three camera on the island itself: the one on the prison, the one on the room with the sixth key, and the one on the entrance to the Tower of Heaven. There are only the three you already knew about, Mr. Kuzushiro. And speaking of the fence...”

Ms. Hitsujiko grabbed the mouse and changed the image displayed on the monitor to the feed of a different camera.

“What are you doing?” I asked.

“It's part of my daily routine,” Ms. Hitsujiko replied. “This is the footage from the surveillance cameras on top of the fence surrounding the island. I check this every day to make sure no one has come to the island from outside.”

When I looked at the image on screen again, I saw that the camera was pointing straight up at the sky. That was right, this island was built like a fortress, with cameras on the fences constantly monitoring for anyone climbing over the fence. Ms. Hitsujiko clicked the mouse. The hourglass symbol that signified the computer was processing something appeared in the center of the screen.

“We use a machine learning algorithm to analyze the feed,” Ms. Hitsujiko explained. “That way, we can save time and only examine the footage where something appears.”

After a few seconds, the hourglass disappeared, and a new window displaying an image was shown in its place. When she saw it, Ms. Hitsujiko looked slightly surprised.

“Something was caught on camera. How unusual.”

“Huh, do you mean...”

“Yes. Something went over the fence.”

That made us all a bit nervous. Ms. Hitsujiko trembled slightly as she clicked the mouse, saying “Well, let's see what it is.”

Something the shape of a ball went over the fence. Ms. Hitsujiko tilted her head and zoomed in. The image quality was a bit grainy, but we could just make out what it was.

It was the helmet from a Western suit of armor. However, it looked like there was something inside, and blood trailed from the neck. In other words, it was...

“Is that the head?”

“Considering everything, it most likely is Otomigawara's head,” Ms. Chiyori answered me. “So, the culprit threw the severed head over the fence.”

The south window of the Tower of Heaven and the fence surrounding Wire Mesh Island were only about 3 meters apart, so it would certainly have been possible to throw the severed head out the window and have it clear the fence.

“But why did they put Ms. Otomigawara's head in the helmet?” asked Yozuki. “Does it mean something.”

“That helmet looks like the same one that was on display in the entrance hall,” said Ms. Chiyori. “I have no idea why they'd put it there. It's a mystery.”

Yozuki and Ms. Chiyori both “hmm”ed in thought. Suddenly, Mitsumura ran from the room without a word. I panicked and went after her. Mitsumura ran through the halls and stopped in the entrance hall of the mansion. There, she looked up at the armor on display there.

The armor was certainly missing its helmet. It looked like the suit of armor had also been decapitated.

“Ms. Kurokawa is right,” said Mitsumura, still breathing heavily after her sprint. “The helmet Ms. Otomigawara's head was inside is definitely the one from this armor.”

The way she said it made me think she understood far more.

“I see, so that's how it is.”

I heard that, but I didn't understand her. Mitsumura stroked her long black hair and turned to me.

“I understand everything now. Who the real culprit is, and how they committed the locked room murder in the Tower of Heaven.”

Those words announced the final end to the serial locked room murder case that occurred on Wire Mesh Island.

Mitsumura spoke to me.

“Now, let's solve the final mystery.”

 

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