His son, Keiichi, has a serious and clean personality and can't stand when Mari and Hiroki flirt. Mari is worried about Keiichi. One day, Mari, who saw Keiichi masturbating, said, "Maybe she's just nervous about women?" Keiichi, who has lost his hoop, presses on Mari regardless of where he is. However, Keiichi's desires do not stop, and Mari himself gets used to the relationship, and Mari becomes addicted to Keiichi's skillful techniques, who are enthusiastic about her sexual studies.
