Maki and her husband, who have started living together with her aging father, Tohru. Tohru was deeply concerned about his beautiful daughter-in-law, Kaoru, and couldn't help but be troubled by her. Every day, he would peek at Kaoru while she bathed... One day, when he spied on his son having sex, he saw Kaoru engaging in self-pleasure beside their sleeping son after sex... Feeling that Kaoru was not satisfied with her sex with his son, Tohru went to Kaoru the next day...