Hiroki Ayase, the protagonist, is at the bottom of his life after failing his university entrance exams. On the advice of his parents, he decides to spend some time at a guest house run by his cousin Yoriko Ooba, a married woman. He is to undergo a period of mental and physical recuperation at the guest house run by his cousin and married woman Yoriko Ooba. Yoriko, whom he hasn't seen in several years, is as beautiful and kind as ever... she is Hiroki's first love. They start living together, but Yoriko's erotic body and adult charms are pushing his own lust beyond its limits. One day, while drying the laundry in the garden, Hiroki finally can't stand it any longer and secretly wanks Yoriko's underwear. He is then witnessed by Fumie Kitayama, a beautiful wife who lives next door, who witnesses his perverted behaviour. Fumie then tells him about an unbelievable code of ethics that has existed on the island since ancient times. Here, a married woman is allowed to perform night-time sex when her husband is not around. The island, a short distance from the mainland, is rich in nature and has a thriving fishing industry, and the men are rarely at home because they are out fishing in the distant seas. The island is rich in nature and has a thriving fishing industry, and the men go out to sea for fishing and are rarely home.