An uncle and his son Daichi visit Ruka's house for the first time in several years. That night, Ruka's uncle is astounded when he invites her to the bath with Daichi. That's because the body of my niece, who I thought was a child, had grown into the body of an adult woman. My uncle, who had a long life without a daughter-in-law in a father-son family, couldn't control his libido when he saw Ruka's nakedness.