Rei Kiriyama, a high school student and pro shogi player, lives alone in Rokugatsu-cho, an old town in Tokyo.
After a game with Kouda, his pro shogi player foster father, Rei heads for the Kawamoto house in Sangatsu-cho.
He receives a lively welcome and dinner from the Kawamoto sisters: Akari, the eldest; Hinata, the middle sister; and Momo, the youngest. But all is not well with Rei…