Marriage isn't about logic

Brothers Asahi Sato (Satoshi Tsumabuki), Hikari (Hikari Mitsushima), Yo (Tasuku Emoto), and Duan (Shuhei Nomura) live in an old house in downtown Tokyo. Since their parents died early in their lives, Asahi, the eldest son, has been raising the brothers as a surrogate parent. Asahi, who is stubborn and old-fashioned, always says that he is the one who has raised them, but this is bothersome to the brothers.