Housekeeper Aika Mirei begins working for the Ichijo household, where father and son live together. Gentle in appearance, Mirei perfectly handles both housework and childcare duties. However, the son, Shota, initially feels nothing special toward her. One day, Shota begins to notice that Mirei's big ass reminds him of his late mother, and his feelings slowly start to change. Drawn in by Mirei's warmth and the allure of her big ass, Shota gradually develops deep feelings for her.