Two years after losing her husband to illness, mother Hikaru lives at home with her son and her late husband's brother and his wife, struggling to support the household financially. Her brother-in-law, a womanizer who runs a hostess club, is highly energetic and spends his days indulging in constant sex with his wife under the same roof. In this environment, the son develops intense sexual fantasies and soon finds himself seduced by his younger sister-in-law. Witnessing these acts, Hikaru eventually becomes involved with her brother-in-law as well. As complicated relationships intertwine, the story takes an unexpected turn.