Yukiko Shimatani is a 39-year-old housewife who has lived happily with her husband and son. However, her world begins to shift when her son starts muttering that her husband comes home late and must be cheating. From that moment on, Yukiko finds more pleasure in masturbation than in sex with her husband, gradually becoming aware of her own desires. But how does her son perceive his mother's changing behavior? A heartbreaking story unfolds as the family's bonds begin to unravel.