After working at the Sanada household for seven years, Keisuke, the eldest son, had to move to Tokyo to attend university. Concerned about Keisuke's ability to adapt to living alone, his father asked Rieko to go with him and take care of things. On moving day, as Keisuke excitedly carried his belongings, he slipped on the stairs. It wasn't a serious injury, but since then, he has been afraid to climb stairs. To reassure Keisuke, Rieko starts flashing her skirt…
