Miori visits a spa recommended by an acquaintance, hoping its treatments will enhance the small breasts she worries about. After a light session she drinks herbal tea and becomes disoriented, awakening bound and helpless. She struggles until a mysterious liquid is rubbed onto her nipples, unleashing pleasure unlike anything she has felt. Men forcibly stimulate her nipples while penetrating her, making her climax repeatedly. Imprisoned inside the spa, Miori begins a hellish routine in which more men arrive each day and smear her breasts and nipples with their semen.