• Togashi, having been struck in the head with a flower vase by Misato, pins her to the ground and starts to beat her. In his blind rage, he threatens to kill Misato, which in turn causes Yusako to panic.

• Fearing for the life of her daughter, Yasuko grabs a kotatsu cord and uses it to strangle Togashi to death. Meanwhile, Misato, no longer pinnned to the ground by Togashi, helps her mother by scratching at Togashi's fingers, which are frantically trying to undo the kotatsu cord around his neck.

• Yasuko resolves herself to pull on the cord with all her might. No sooner does she strengthen her resolve than does she discover that Togashi is dead. Both she and Misato are shocked and at a loss about what to do.

• Then, a mysterious knocking is heard at the door as Yasuko is frantically considering what to do. It's Ishigami. Yasuko attempts to hide the evidence of her struggle with Togashi and moves the corpse under the kotatsu table. She tells Ishigami that she killed a cockroach, and that's all. Ishigami then returns to his apartment.

• Yusaku contemplates turning herself in to the police. She doesn't wish for Misato to have a murderer for a mother. At the same time, she doesn't wish for Misato to be implicated in the murder and face criminal charges. Misato grabs the cordless phone and prevents Yusako from using it to call the police. As Yusako approaches the phone, resigned to the fact that she will have to tell the police, the phone rings.

• It is Ishigami. He has basically deduced everything that happened in Yusako's apartment and asks her how she will dispose of the body. Yusako tries to deny it but then agrees to let him come over. She also tries to deny Misato's involvement, but Ishigami can infer this as well. It is pointless trying to deceive Ishigami, whose deductive reasoning skills greatly impress her.

Ishigami offers to help Yusasko but is content with just saying nothing or with her going to the police. Eventually, Yusako, at the urging of Misato, agrees to accept Ishigami's help in covering up the crime.

• They promptly get to work covering up the scene of the murder. Ishigami moves the body to his own apartment, where he strips it naked. He asks for biographical information about Togashi and considers all the possible ways that the body might be identified. Finally, he indicates to Yusako that it will be necessary to construct an alibi and promises her that logic will help them extricate themselves from their situation.