Nanako, a capable senior, and Rui, a clumsy junior. Recently, the two started dating after Nanako gave in to Rui's passionate advances. However, Nanako made a promise to him as a condition of their relationship that she would never tell anyone about their relationship, not even to her company or her husband. One day, Rui was so angry at Nanako for making a mistake at work that he broke his promise to Nana and committed a workplace taboo.