For years, despite knowing it was wrong, Kaede and her son Shintaro had continued their physical relationship. However, when Shigefumi quit his corporate job and began working from home, opportunities for sex diminished, causing their desires to grow stronger each day. One day, Shigefumi went out jogging. Seizing the chance, Shintaro approached Kaede for sex. Torn between thrill and guilt, the two began a secret affair, meeting only during the times when her husband was away.