Lately, Yumi has been worried about her weight gain due to frequent business dinners. For her health, she starts going to the gym with her subordinate, Hajime, using the company's welfare benefits. However, being sexually frustrated and having gone a long time without intimacy with her husband, she decides to toy with Hajime's perverted nature—since he's always staring at her ass—and uses him to relieve her own stress. Hajime, who was already captivated by her voluptuous, curvy ass, is bewildered by this sudden and unreasonable reverse sexual harassment, but he can't resist the caresses that hit his exact fetish and gets swept away. Before long, the two develop a relationship where they secretly indulge in pleasure even during work hours...