After four years of marriage, Sakura, a wife, was living a frustrated life with her husband as their nighttime activities had decreased. One day, when she visited her father-in-law's house with her husband, she found her father-in-law, who had become so senile that he had even forgotten his son's face. Worried about her father-in-law, Sakura volunteers to look after him, but he asks her to be his model for him as he has taken up painting as a hobby. Sakura's voluptuous hips inspire his father-in-law to paint, but before he knows it, his crotch has become erect. "This is art!" Her father-in-law rejoices as he stares at Sakura's moist crotch. Sakura is also aroused by her father-in-law's "brush".