Forty-year-old Mami Kotomiya is a full-time housewife whose daily life revolves around her three sons. Despite having a strong sex drive, she holds a firm belief that infidelity is absolutely unacceptable, and until now, her only sexual experiences have been with her husband and a former boyfriend before marriage. When her husband was transferred for work and lived away from home for two years, she endured sexual frustration without cheating, even seriously considering working at a brothel. What finally pushed Mami to make her debut was her husband's erectile dysfunction. After two decades of loyalty in their relationship, her long-held chastity has now crumbled under overwhelming sexual desire. Watch as this G-cup housewife boldly abandons her fidelity and indulges in her first-ever act of infidelity, determined to enjoy it to the fullest.