Returning home to their parents' house, eldest son Taro and younger brother Kazuya are joined by their wives—Taro's wife Yoshie Mizuno and Kazuya's wife Shizuka Akiyama—bringing lively energy to the household after a long time. Shizuka, concerned about Kazuya's lack of stable employment, begins developing feelings for Taro. Meanwhile, Kazuya finds himself drawn to the gentle and supportive Yoshie. The brothers, already distant, grow further apart as each becomes emotionally entangled with the other's wife. Kazuya secretly touches Yoshie, while Taro suppresses his desire for Shizuka. Yet their secret encounters under one roof can't stay hidden forever, and the truth will soon be exposed to both couples.