Rei Kiriyama's parents and younger sister died in an accident in his childhood. He then started living with the family of Masachika Kōda who was a friend of his father. Reaching adulthood, Rei left his foster family thinking he was only causing trouble. He now lives alone and has few friends. Among his acquaintances are three sisters of the Kawamoto family—Akari, Hinata, and Momo. As the story progresses, Rei deals with his maturation both as a professional shogi player and as a person, all the while strengthening his relationships with others, particularly the Kawamoto sisters.
