Haruka's family purchased a house, where her daughter and son-in-law would live. Drawn to a close, Ayane—the mother-in-law—feels saddened by the nearing end of their cohabitation. On a certain day, by chance, she discovers her son-in-law Makoto has a large penis. Ayane, who had been sexually frustrated, couldn't resist her desires and succumbed to his large member. Enchanted by her lascivious behavior, Makoto becomes addicted to the covert sexual services provided by his mother-in-law within the household. What was supposed to be a temporary relationship until the move, eventually evolves to where he can't endure without Ayane's body.