Yuuki is a high school first-year student who attends the same school as Saki and is a member of the mahjong club. She is highly skilled, though cannot stay focused and makes more mistakes as the game progresses, so she is made the first to play at the mahjong tournament. She is often seen eating tacos, which increases her skill when playing mahjong. Additionally, food with names similar to tacos, like takoyaki can increase her skill partially as well.

Saki
Saki Miyanaga is a high school freshman who doesn't like mahjong. Ever since she was a child, she would lose her New Year's gift money during her family mahjong game. If she won, her parents would be upset, and if she lost, well, she lost. As a result, she's learned to play in such a way that her score differential always remains ±0: not good enough to win, but not bad enough to lose. When we meet her, she's being dragged to her school's mahjong club by an old friend. How will a girl who hates mahjong, yet has become adept at the game as a result of her upbringing, survive in this environment? (Sources: ANN and AniDB)