Struggling with unfamiliar household chores, Saki does her best as a new mother. Meanwhile, her stepson Daisuke finds it hard to get along with her, as their personalities are complete opposites. From differences in temperature preferences—one always hot, the other always cold—to clashing lifestyle habits, they seem incompatible. Yet, Daisuke can't help but notice how lightly Saki always dresses. To a young man his age, her appearance holds a special allure. One day, Daisuke discovers an adult toy in Saki's room. Just then, Saki walks in, fresh from the bath. From that moment on, their relationship takes a dramatic turn.