After a fight with her husband, mother-in-law Sachiko comes to her daughter and son-in-law's house. She drinks and complains to her daughter and son-in-law, and then falls asleep. The son-in-law is intrigued by his mother-in-law's voluptuous body, but carries Sachiko to the bedroom. Sachiko jokingly tries to seduce him, saying, "Let me take off your clothes." The son-in-law gets an erection at the sight of her braless breasts, and Sachiko is pleased when she notices this, and after that she begins to tease him and seduce him frequently. One day, when the wife goes out to a girls' night out and they are left alone, the son-in-law and mother-in-law finally end up together...