Reiko Nakamori lives peacefully with her stepson, Atsushi, the child of her husband who disappeared in an accident. Though not related by blood, they share a warm, loving mother-son bond. One day, everything changes when Atsushi attempts to secretly film Reiko while she showers. Confronted, Atsushi confesses he was blackmailed by the person responsible for his father's accident and had no choice. Deeply responsible and concerned, Reiko invites the blackmailer to their home to uncover his true intentions. But this decision triggers his uncontrollable desires, plunging Reiko into unbearable humiliation and transforming her into his sex slave.