Natsumi, a housewife, has built a happy family with her husband, Yudai, who works for an advertising agency, and her only son, Nautical Mile, who is a high school student. However, Natsumi and Yudai have been sexless since the birth of Nautical Mile. It is the tacit understanding of the couple that “sex is done outside the home”, Natsumi enjoys affair with Tanaka, an elderly caregiver who is a part-timer, and Uchimura, who met at a joint party, and Yudai enjoys an affair with a married woman, Miki, who rides on a ball. There was. Meanwhile, Natsumi reunites with her former neighbor, Ryoko …