Noah and Nobuo have been married for three years and are living a happy married life. One day, Nobuo brings his subordinate Kuroda home. After that, Nobuo starts to invite Kuroda over to their house frequently. Noah is gradually Kokoro by Kuroda, who is younger and more muscular than her husband, and they end up having a relationship. However, there is an unexpected truth. In order to improve their married life at night, which has become monotonous.