Married masseuse Rei struggles with stagnant performance, but under the guidance of her trainer Ichijo, who tells her "start by learning your own pleasure," she begins transforming into a voluptuous, sensual woman. She discovers ecstasy through anal stimulation, and even in public bars, she's subjected to humiliating sessions in blind spots from customers. Day after day, she undergoes relentless triple stimulation—her anus, pussy, and clitoris tormented without mercy. She repeatedly reaches climax through deep anal penetration by a huge cock. Rei crawls on the floor, drooling, thrusting her ass, desperately chasing pleasure, moaning, "I'm a filthy anal bitch. Please give me harsher training."