Five years after losing her husband, widow Mayumi tries to cope with loneliness by masturbating every night. One day, her son brings home a friend who immediately becomes fixated on her voluptuous breasts, secretly drawn to her charm without her noticing. But Mayumi catches the young man's gaze and, giving in to desire, seduces him and indulges in his youthful body. Witnessing the act, her son is overwhelmed by jealousy and impulse, turning his eyes toward his own mother. Soon, Mayumi gives in to her suppressed lust, and the two spiral into a frenzied, incestuous relationship.