Rei Kiriyama, a 17-year-old who also makes a career as a professional shogi player, has very little else in his life. He owns his own apartment, is single, and has few acquaintances who he would consider pals. Only the nearby Kawamoto family, which includes older sister Akari, younger siblings Hinata and Momo, as well as several cats, is in closer contact with him. The sisters make an effort to lift him out of his gloomy situation, but they still struggle with the effects of their history on both themselves and Kiriyama.
