This is the Kitahara household. To his son Haruyuki, who seeks sex through vaginal intercourse, Natsumi says 'Only that is not allowed' and permits anal sex. Natsumi has reached orgasm through anal sex from some point on. On the other hand, this is the Matsumoto household. To his son Seiji, who wants to have anal sex with his mother, Marina says 'Only that is not allowed' and permits vaginal intercourse. Seiji dreams of the day when he can have anal sex with Marina... One day, Haruyuki and Seiji decide to take a certain action but come to realize an issue with their asses...
