最近、取引先との付き合いで食事会が増え、体重増加に悩むゆみは健康のためにと会社の福利厚生で部下・ハジメと共にジム通いを始めるが…。旦那ともご無沙汰で欲求不満だった彼女は、普段からやたら尻を見てくる彼のスケベ心を弄び、自分のストレス発散に突き合わせるのだった。元々、彼女の豊満なムチ尻に心奪われてたハジメは、突然の理不尽逆セクハラに戸惑いながらも性癖を直撃する愛撫に我慢できず流されてしまう。そして、いつしか2人は業務中にもこっそり快楽を貪り合う関係になって…。

Recently, Yumi has been worried about gaining weight due to the increased number of dinner parties she attends with clients. To improve her health, she starts going to the gym with her subordinate, Hajime, through the company's employee benefits program. However, she's also sexually frustrated due to a lack of intimacy with her husband. She begins to play with Hajime's lecherous desires, noticing his constant stares at her buttocks, using him as a way to relieve her stress. Hajime, who was already captivated by her voluptuous buttocks, is bewildered by this sudden and unreasonable act of reverse sexual harassment, but he can't resist the caresses that directly hit his sexual desires and is swept away. Before long, the two begin secretly indulging in pleasure even during work hours…