When the Detective Work is Done, I'll Die

Chapter 12

Furudou lifted his face, which had been crying, and dropped his glasses again.

"W-What are you saying? S-Suddenly calling it murder...! That was really! Really self-defense... And just now you looked utterly crushed, didn't you..."

"Ah..."

"Saying whatever pops into your head just because you think it's too late to take back is no good..."

Ah, yes. When the detective hit me, I must have looked as though I were drowning in despair. But it was nothing. I had only pretended to take the detective's words seriously. That way I could better grasp how terrible the trap he had laid for us was.

In the end, it didn't matter at all. It had simply been a waste of time to listen and get punched.

All the preparations to accuse Furudou as the murderer were complete. If it had truly been self-defense, the detective's words might have been spot-on. But if it was murder, the story changed.

He had to pay for his crime, or things would get ugly. If he didn't reflect on his actions in prison, he would likely repeat the same mistake. To prevent that, I would now charge Furudou as the murderer.

"I have proper evidence. Evidence that it was murder...!"

"Th-Then why did you give that reasoning earlier?"

Furudou's question can be answered with three reasons.

The first is to make the culprit let down their guard. If the culprit thinks they've cornered the opponent with their own reasoning, then getting reversed would deal enormous mental damage. After all, if they suffer a serious blow from someone they thought was nothing special, their overconfidence would send their mind into panic.

If the culprit, overwhelmed by shock, admits "I'm the culprit," that's a great success. Well, in this case the odds of surrender are low.

So the first reason isn't that important.

The second is to learn the detective's objective. Just as expected, he clearly told us he intended to rampage and destroy the evidence. That's not much of an issue either.

The third is the most important. It'll be the crucial key to advancing the reasoning smoothly. I'll explain it.

"It's to have you admit from the start that it was self-defense and to hear how you dealt with the sword. If there's a contradiction in that, I can easily prove it wasn't self-defense... Huh? Ah, Miiko!"

There, Miiko gave me even sharper support. The ever-thoughtful girl snatched my smartphone from my pocket. I wondered what she was doing in the middle of our important discussion, but she opened the recording app right in front of me.

"Sorry. I figured I should record the reasoning show on this side too. It'll be a pain if I'm told to repeat the details later. And... the reasoning show up to this moment is stored on my phone."

"Ah, right. Got it. Thanks! Furudou, listen up. We reasoned it was self-defense, and you told us the story of when you killed Mr. Koyama, right? Here it is."

Until now, the smartphone had been recording. In other words, from Miiko's own phone, which had secretly captured the audio, a certain voice was now played.

"He came at me."

Furudou's voice. Followed by mine.

"So he charged straight at you with his body?"

Furudou's voice again.

"That's right! I didn't understand what was going on...! One moment he was angry, the next he was attacking me."

Up to this point, nothing is off. Even the detective is roaring, "So what of it!?"

But I want everyone to think carefully. Furudou's right arm had been slashed vertically with a sword. However, how would one normally slash vertically with a sword?

"Um, let's try this."

I rolled up some nearby newspaper to imitate a sword. I had Miiko set her smartphone down and play Furudou's part. Naturally, the one holding the sword was the victim—my role as Mr. Koyama, said to have attacked first.

First I stood directly in front of Miiko. But no matter how many times I swung the rolled newspaper, I couldn't slash her right hand vertically. As long as I held the sword in my right hand, I couldn't vertically slash her right hand, which from my perspective was on the left.

If I tried slashing vertically from an angle, the sword's angle would be off and I couldn't make a clean straight line. When slanted, the area of skin struck inevitably increases. From how it's cut, you can tell where the blade came from.

At our demonstration the detective stamped like a child, shouting complaints. "Don't mess around!"

"Hey! Just hold it in your left hand, right!? What!? Because you can't cut like this, you're deciding everything Furudou said is a lie!?"

"Ah... Then you're saying you can make a clean vertical slash with your non-dominant hand. Let me be clear: you can't cleanly slice with a sword using half-hearted strength. If it's not your dominant hand, it's impossible to cut straight and cleanly with enough force to draw blood!"

"Hah!? Huh!? Ah!? Dominant hand!?"

The detective is flustered by my rebuttal. Meanwhile Mr. Hida passes information to the detective. Yes, that's right. It was Mr. Hida who told us about the pen's placement and the victim's dominant hand.

"Definitely the right hand. The right hand! So then... to slash straight with a thin vertical line, the boy would have to move more to the left from his perspective."

Exactly. I moved so that I was to Miiko's right. Then I could cleanly slash her right arm vertically with the sword in my right hand.

However, the charge Furudou described is impossible.

"So? Furudou? Miiko is blocking my path with the sword. If I charge, my stomach might get stabbed, right? How did you do it!? How could you charge in this situation!?"

Sweat pouring down his face, Mr. Furudou pokes his own head with a finger and offers an excuse.

"Ah, th-that's right, I was holding it with both hands. Both hands on the sword... Then I put my right hand forward, and at that moment—slash...!"

"Then let's try that."

Following Furudou's instructions, we tested it. Whether a charge was possible or not became obvious at a glance.

Assuming this situation, how would Furudou have to move to push Mr. Koyama down? The answer is simple: he would have to impale himself on the sword Mr. Koyama is holding.

"Ugh...!"

"So? Furudou. Can you charge straight like this? You said it yourself. If you hadn't done it, you would've been killed. In other words, according to your story, Mr. Koyama never sheathed his sword. After all, Mr. Koyama was trying to kill you. If he had sheathed his sword even once, he could've been caught and wouldn't have been able to kill."

"Ah...!"

Furudou's face grows paler. I press on with my reasoning.

"In other words, the story that Mr. Koyama attacked you with a sword is a complete lie! You tried to make it look like the now-dead Mr. Koyama had attacked you. You slashed your own hand with the sword. But you messed up. You didn't think carefully about which hand to use or how to cut it to make it look like Mr. Koyama did it. You cut it in a panic."

Probably realizing it would be bad to keep pressing the lie about the sword, he suddenly tried to change the subject.

"W-Wait a minute. I wouldn't have had time for that kind of staging... What if someone had come during it? Like Mr. Hida...! If you can't understand, even if I killed with intent, I wouldn't have had the composure to stage it so precisely."

"...That angle, huh. I think there was plenty of time. The memo about the guests had it written: 'high-school girl, 4 p.m.'—our scheduled arrival. If you have an appointment, you usually don't schedule another meeting around ten minutes before or after. So all you had to do was finish everything before four, when we'd come. You had the composure."

"B-But Mr. Hida..."

"Mr. Hida is easy. Just ask him about the shopping—Mr. Koyama would've told him. That noisy Mr. Koyama would've casually asked the housekeeper to buy an outrageous amount. If you just asked what time he left, you could calculate how long it'd take him to return, giving you the composure."

I crush him utterly with logic. Furudou's face has gone beyond pale to white. Still, he desperately throws out counterarguments.

"Ugh... Even so, you can only prove it wasn't self-defense. It might've been manslaughter or fatal injury! Don't you consider the possibility it was an accident...?"

"Ah, I don't. If there was intent, it's no longer manslaughter or fatal injury. If you consider why the money was scattered around this room, you can prove you had planned intent to kill!"

Everyone besides Miiko freezes. They're surely thinking: can he really prove intent to kill? Can he truly read what's in someone's mind!