In the 21st century, mahjong has become a global entertainment activity, and related competitions are held in various places. Among them, the national mahjong competition held among high school students is the most authoritative. At the same time, some players with outstanding mahjong talents have also surfaced one after another, including the genius girls Miyanaga Saki (voiced by Kana Ueda) and Haramura Kazu (voiced by Ami Koshimizu). In the mahjong field, Haramura Kazu values experience and data, and classifies opponents according to his rich experience in battle to gain an advantage. Miyanaga Saki has completely different skills. No matter what kind of game she encounters, she can end the game with an undefeated result. After a duel, the two who did not know each other decided to join the school's mahjong club, defeat the enemies that kept emerging on the road, and finally dominate the national competition.