Tatsuo goes to visit his girlfriend Shunka's house. He happens to meet her mother, Murasaki, and becomes aroused by her. Murasaki is also not having sex with her husband, so she becomes aroused by the sight of a young man and masturbates. Witnessing this, Tatsuo can't think of anything else but Murasaki. Unable to resist, he pressures Murasaki into a relationship. Even though Murasaki tells him it's not right, he betrays his daughter and asks for her cock.