Saki walks into a high school mahjong club having spent years deliberately breaking the game to protect herself, which means every hand she plays is a small act of sabotage dressed up as perfection. The show treats a tile game most people don't understand as a psychological battlefield where the real enemy is your own need to survive. A girl who learned to lose so well that losing becomes her only way to win finally meets people who actually want her to play.

Saki Miyanaga is a first-year high school student who has hated mahjong since childhood. In her family's games, winning upset her parents and losing cost her the New Year's gift money, so she learned to finish every game at exactly plus/minus zero, a result far harder to pull off than simply winning. Her friend Kyoutarou Suga pulls her into the school's mahjong club, where she meets Nodoka Haramura, last year's national middle school champion, and fellow member Yuuki Kataoka. Club president Hisa Takei spots Saki's strange playstyle and tests her true strength, which bruises Nodoka's pride and starts the two off badly. Once they clear things up and become friends, Saki slowly warms to the game again, and the club sets its sights on winning nationals. It is a slice-of-life sports series built around competitive mahjong.