Yohei lives with his mother, Kaho, and cousin, Fumika, in a happy home. But one day, Kaho reveals to Yohei that she is his father’s older sister, not his mother…. She also informs him that his mother died many years ago. Yohei is taken aback by this news, but he soon begins to regard Kaho as a lady rather than his mother. Ikue, a woman, moved into a house next to his a few days later. When Ikue first meets Yohei, she bursts into tears, and Kaho becomes pale. Ikue explains that she is Yohei’s mother’s relative and that she wishes to accept him as an adopted child. Naturally, Kaho and Fumika decline…. Their filthy and erotic life begins on that day….