When Saki begins high school, she faces a challenging situation during family mahjong games. Winning or losing both come with negative consequences, leaving her in a predicament. To solve this, she creates a unique strategy - aiming for the elusive plus/minus zero score, achieved solely by luck. Despite its difficulty, Saki becomes skilled in achieving this score, expertly balancing between victory and defeat. Although Saki has never enjoyed mahjong, her middle school friend Suga Kyotoro persuades her to join the school's mahjong club. With her developing skills and remarkable luck, she becomes a formidable opponent, even surpassing the nation's top-ranked middle school mahjong champion.