Suspect

Ishigami, a reclusive math teacher who lives next door, buys lunch from Yasuko's restaurant and greets her in the morning. Those exchanges are described as the brightest part of his day, offering a rare glimpse of warmth in his quiet life. The ritual establishes the bond that will later become central to the mystery.

Togashi storms into Yasuko's apartment to extort money, his threats escalating into violence. Yasuko and Misato end up killing Togashi in their apartment to protect themselves. The murder immediately creates a crisis that forces them to think about covering it up.

From his room, Ishigami overhears the commotion and realizes that a murder has occurred. He approaches Yasuko and Misato with a calm, calculated offer of help, motivated by loyalty and his own moral code. He begins to plan how to dispose of the body and manage the fallout.

Ishigami assists in disposing of Togashi's body and devises a step-by-step cover-up to mislead investigators. He uses his intellect to control the flow of information and create plausible explanations. The plan is systematic, aiming to minimize questions and buy time.

The corpse is discovered and identified by authorities, triggering suspicion toward Yasuko. As investigators connect the dots, the mother becomes the prime suspect, with Misato under scrutiny as well. The case suddenly shifts from a quiet tragedy to a high-profile inquiry.

Detective Kaoru Utsumi and her superior Shunpei Kusanagi seek the help of Professor Manabu Yukawa, hoping his analytical mind can illuminate the case even though it lies outside physics. Yukawa initially refuses, insisting the case has nothing to do with his field. The invitation to investigate becomes a test of his curiosity and sense of duty.

Hearing that Ishigami is the suspect's neighbor, Yukawa changes his mind and agrees to engage with the case. He reunites with Ishigami, rekindling admiration and curiosity, and starts to doubt whether Ishigami is involved at all. The dynamic sets up a tense intellectual dance between old friends.

Yukawa launches his own investigation, testing the suspects’ alibis and the logic of the murder. He digs into the limited, seemingly straightforward clues and begins to suspect that nothing about the case is as it appears. The investigation pits his analytical rigor against Ishigami's flawless schemes.

A high-stakes intellectual duel unfolds as Ishigami tries to shield Yasuko and outsmart Yukawa. He carefully structures defenses and counterarguments to keep the truth from surfacing. Yukawa pushes back with relentless logic, narrowing the path to discovery.

Yukawa finally pieces together the truth behind the murder through deductive reasoning and the human dynamics at play. The solution reveals the complex motives and measures used to commit and conceal the crime. The moment showcases Yukawa’s brilliance, even as it unsettles him.

The revelation is shocking and deeply unsatisfying for everyone involved. It exposes the cost of the crime without delivering real justice or relief to the people affected. Yukawa, who usually remains detached, is visibly distraught by the outcome.

With the case closed, the police have their closure, but the personal costs linger for Yasuko, Misato, and Ishigami. The accuracy of the solution contrasts with the moral ambiguity of the events that preceded it. Yukawa's emotional reaction underscores the human toll of solving the mystery.