Tatsuo visits his girlfriend Shunka's house and unexpectedly encounters her mother, Yukari. Tatsuo becomes aroused by Yukari, who is also experiencing sexual frustration with her husband. Witnessing Yukari's self-pleasure, Tatsuo becomes obsessed with her. Unable to resist, he pursues a relationship with Yukari, who, despite her reservations, seeks out his cock, betraying her daughter.