Yuuya had recently been visiting his girlfriend's house frequently. His purpose was to meet her mother, Yuzuki. While dating her, Yuuya was also conscious of Yuzuki as a woman. This was not permissible. But... The young couple and the mother. With complicated feelings, the three's relationship was maintained on a precarious balance. However, one day, that relationship collapsed at once. Yuzuki was the one who caused the collapse. When they were alone for the first time, Yuzuki showed her first feminine expression...