Married woman IORI TSUKIMI joins a gym to lose weight. Breast-obsessed trainer Yoshida knows he should look away, but he cannot stop staring at her huge tits. Once she changes into workout clothes, he teaches her stretches, weight training, and stationary cycling while sporting an erection. Soon she is drenched in sweat, and her clothes turn so sheer they may as well not be there, leading into rough breast play, sex, and a creampie.