Nanami returns to her husband's parents' house during the Obon holidays. She has known her husband Takaya since their school days, and Toru, who is now her father-in-law, has always been close to her. Toru was kind, reliable, and someone she looked up to. As an adult, this changed into feelings for him as a man of the opposite sex. Then, when Takaya is late returning home for work and she is left alone with Toru, Nanami can no longer suppress her feelings, and she seduces Toru, who is supposed to be her father-in-law, with her obscene breasts...