Saki Sunohara, 57, has been married for 30 years and is a mother of four, with children ranging from 19 to 28 years old. Her large family life is lively and fun, but with someone always home, her marital relations have suffered. She and her husband can only manage quick standing-back encounters in the bath. Saki believed this stifling sex life was something she had to endure until her sons became independent. However, when her eldest son decided to live at home after finding a local job, her patience reached its limit. The accumulated frustration of this hypersexual mother reached a critical point, leading her to dive into the world of infidelity for the first time.