In a room in a certain home, a man is hanging from a beam. A woman puts a suicide note at her feet and looks up at the man with a hollow expression... One day, a woman visits Mikoshiba. She's Mikoshiba's younger sister, Koda Azusa, who he hasn't seen in more than 30 years. Azusa tells him a shocking fact, their mother has been arrested for murder. Mikoshiba's mother, Ikumi, is suspected of killing her second husband, Narizawa Takuma, by making his death look like a suicide. Mikoshiba tries to coldly dismiss Azusa's request to defend her but Azusa tells him no one else will take the case because no one wants to defend the mother of a murderer. Mikoshiba goes to meet Ikumi at the detention center. Despite his mother being pleased to see him again, he treats the matter as a lawyer and not as a son. The case looks bad for Ikumi due to the evidence left behind.