Yumiko Endo, 30 years old. After losing her mother at the age of 18, she has lived with her stepfather ever since. On the surface, their father-daughter relationship appears calm and modest, but in reality, they have maintained an intimate, marital bond. They've kept this secret hidden from everyone—until now. As summer fades and autumn approaches, her uncle Goro arrives from Tokushima and begins doing something in the next room. The sounds reach Goro's ears, threatening to expose the forbidden relationship between Yumiko and her stepfather.