Kiriyama Rei is a 17-years-old shogi (Japanese chess) player. He debuted as a professional shogi player when he was in middle school. He lives by himself in Tokyo, because his parents and younger sister died in a traffic accident when he was little. One day, Kiriyama Rei meets three sisters who are his neighbours. The three sisters are Kawamoto Akari, Kawamoto Hinata and Kawamoto Momo. This is his first meeting with someone
