Miyanaga Saki, a first-year student at Kiyosumi High School, lacks enthusiasm for mahjong and plays it so that it will end with neither a win nor a loss. One day, she is influenced by Haramura Nodoka’s genius mahjong tactics and decides to join the mahjong club. Nodoka is the titleholder of the national junior high school mahjong tournament. Together with Nodoka and the other club members, Saki contends for the title against formidable opponents.