At a hotel during a business trip, salaryman Ooki meets Sumire, a big-breasted, melancholic cleaning staff. Captivated by her mysterious masturbation, he is drawn to her charm and pulls her into his embrace. Feeling lonely, he indulges in pleasure, savoring Sumire's body. However, she is secretly under the mental control of the hotel manager, hiding a masochistic side. Ooki gradually discovers the truth and becomes entangled in Sumire's true nature.