Married for 30 years, 57-year-old Sunohara Saki. With children ranging from 28 to 19 years old, she is a mother of four living with her kids. Life in a large family is lively and fun every day, but with someone always at home, the couple's intimacy is difficult, and she can only manage quick standing doggy-style sessions in the bath with her husband. "This suffocating sex life is just something to endure until our sons become independent..." Saki thought, but when her eldest son, who found a job locally, decided to live at home, she finally reached her limit. The accumulated frustrations hit a breaking point, and this oversexed mother plunges into the world of illicit pleasure for the first time.