Maki, Hisae's daughter, is happily preparing for her upcoming wedding with her boyfriend, Ichiro. However, Hisae senses that Ichiro seems emotionally distant, as if his heart belongs to someone else. One day, after Hisae steps out of the bath, she finds Ichiro standing there holding her underwear. He panics, apologizes frantically, and quickly runs off. From that moment on, an undeniable and illicit relationship begins to develop between Hisae and Ichiro.