Sakon deduces from evidence that a left-handed person committed both murders, but everyone there is right-handed. Sako discovers that Aoki, an assistant with his head bandaged from a fire years earlier, is really left-handed. Sakon uses Ukon to mimic the voices of the dead men, tricking Aoki into confessing that he is the killer. It is revealed that Aoki is in reality the ex-husband of Keiko, Hayami's partner, and Aoki is seeking revenge for the death of their daughter years earlier in the fire that disfigured him when he tried to save her.