I looked in Kirigiri's direction as if seeking help. Kirigiri shrugged her shoulders and let out a soft sigh. "Yui-onēsama is not the perpetrator."
Kirigiri spoke up. "K-Kirigiri-chan!"
"Oh? right. Then can you prove that your onēsama is not the perpetrator?"
"Of course." Kirigiri took out the tape measure from her pocket. "By using this."
"...What does that mean?"
"Simple calculation problem. I measured the chain on the handcuffs and it's about 20 meters. From this length we can conclude that Yui-onēsama couldn't reach the crime scene."
"Huh? The crime scene's adjacent, yeah? The windows are right next to each other. 20 meters are enough."
"No, the length is not enough."
Kirigiri approached the bed and pulled Yukimura's left arm out from under the blanket. A part of the chain that extends from the handcuffs fell to the floor with a clank. The chain is 20 meters and connects to the handcuff on my right hand.
"Yui-onēsama and the victim are sharing this chain." Kirigiri grabbed the chain and said. "Now then, let's measure the length of the chain from the victim's left wrist to the entrance of this room."
Kirigiri extended the tape and accurately measured the length of the chain.
"About 3 meters. To simplify things, we can omit the numbers after the decimal point."
"There's still 17 meters."
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Kadomi said impatiently while putting his hands on his hips.
"That's right. Incidentally, the central hall is a regular pentagon with a side length of four meters. Knowing this, and then calculating it, you will know that it's impossible for Yui-onēsama to commit the crime."
"I see... Indeed, no doubt."
Yūhain said convincingly. He is very picky about architecture, and he may have grasped the approximate distance from the design.
"Wh-what do you mean?" Kadomi tilted his head.
"As measured just now, the length of the chain in the room is 3 meters. Then the chain extending to the hall will be at least 3 meters long when it reaches the adjacent room of Yui-onēsama. This is the length of the chain when it is taut. Then 6 meters from the entrance of Yui-onēsama's room door to the window, which adds up to 12 meters in total."
"8 meters left... In that case, it'll be enough to reach the next room, right?"
"No. In this star-shaped building, the distance between the vertices of adjacent triangles is about 10 meters. The remaining 8 meters of chains are still 2 meters short. Roughly calculated, Yui- onēsama wouldn't have even reached the window of the next room. If she wanted to stab the victim with the knife, she would've needed a few more meters."
