Shiori has a college student’s son, Oga. And Kosuke, who is the remarriage partner, had a daughter, a song, of a school student. They should have had a happy remarriage … However, the existence of Shiori, the mother-in-law for the song, makes her father unbearable. Due to the distorted affection, the song makes Shiori rape, threatens with a weapon and forces incest with his son.