Hinako joins a gym to shape her body for her husband, but her ass-obsessed trainer turns every lesson into sexual harassment. Soon she is drenched in sweat and pussy juice, and the trainer loses control and assaults her. Though she hates what is happening, his stamina brings her unprecedented orgasms and squirting, especially when he pounds her from behind. Guilty toward her husband yet addicted to that overwhelming pleasure, Hinako keeps returning to the gym to be taken again.