Iroha is a newlywed. After registering her marriage and living with her husband, she started gaining weight... She wants to lose weight and get back to her previous figure before the wedding, so she starts going to a personal gym three times a week. The trainer is gradually drawn to her beautiful body and the sex appeal of the married woman, and Iroha is drawn to his muscular body. Before they know it, they are lusting after each other and forgetting about training. Things escalate more and more, and she calls in another trainer for a threesome creampie muscle affair.