Ninomiya, a sober OL. From her day-to-day life, she was a very inconspicuous presence in the company. One day, on her way home from a drinking party, she is approached by a senior office worker, Sato, and she ends up having sex with Sato. Sato only thought of Ninomiya as a convenient woman for her, but she had two secrets in Ninomiya. That is, she is a slut and a married woman.