Rikka Inui, active as a model, is always conscious of maintaining her slender figure. At her boyfriend's suggestion, she visits a stretching studio, only to discover it's actually a lewd massage parlor. Despite her strong self-awareness and discipline, she's placed in vulnerable positions where her breasts and genital area are persistently groped, causing her to involuntarily become aroused. During the session, explicit photos are taken without her consent, giving the therapist leverage over her. Blackmailed, she agrees to in-home treatments and ends up receiving deep vaginal penetration from the therapist right under her boyfriend's nose. She writhes in ecstasy and reaches orgasm, yet cannot shake the humiliation of being deceived and violated. However, her body craves the sensation, and unable to resist the growing desire, she uses "waist training" as an excuse to willingly return to the erotic masseur.