Due to childhood circumstances, first-year high school student Saki Miyanaga hates anything related to mahjong. When she does play the game, she keeps a low profile to avoid standing out. One day, her friend Kyoutarou Suga drags her along to the school's mahjong club. There, she meets Nodoka Haramura, the champion of the previous year's national middle school mahjong championship, and Yuuki Kataoka, a fellow club member. As the club play a few rounds, Saki attempts to hide her talent. However, the club president, Hisa Takei, notices Saki's unusual playstyle. Realizing her potential, she puts Saki's real ability to the test—proving her to be more talented than expected. This revelation damages Nodoka's pride, and their relationship gets off to a rocky start. Saki ends up joining the club, and after clearing up the misunderstandings between her and Nodoka, friendship blooms between them. As Saki slowly warms up to mahjong once again, she and the rest of her club only have one goal—to win nationals! [Written by MAL Rewrite]

The Achiga Girls' Academy in Nara once defeated regional mahjong powerhouse Bansei High School. It advanced into the national team semifinals but lost to the eventual champion, and the mahjong club was later disbanded.

Six years later, elementary school student Shizuno Takakamo befriends transfer student Nodoka Haramura. The two eventually enter Achiga Girls', but Nodoka transfers out of the school in the second year.

When Shizuno sees Nodoka on television the following year as the national middle school individual mahjong champion, she decides to revive Achiga's mahjong club.

Saki Miyanaga, along with the rest of Kiyosumi High School's mahjong team, proceeds to the national level of the Interhigh Mahjong Championship. However, reaching the top will prove difficult as she faces opponents on par with and, quite possibly, exceeding her skills. Even so, she refuses to back down, vowing to stop at nothing to fulfill her goal: to see her sister face-to-face once more. [Written by MAL Rewrite]

Kouta Hasegawa is a completely normal high school student who likes his Pompompurin stuffed animal, a Sanrio character modelled after a Golden Retriever, which his grandmother gave him when he was young. However, an incident in which other kids accused him of being girly for liking Sanrio characters made him ashamed of his attachment to Pompompurin. Through a series of unexpected events, Kouta ends up meeting others at school who also like Sanrio characters—Yuu Mizuno, a flashy boy who is popular with girls; Shunsuke Yoshino, a member of the soccer team; Ryou Nishimiya, an underclassman who is a library assistant; and Seiichirou Minamoto, the student council president. Through his new friends, Kouta learns that there is no need to be embarrassed for liking Sanrio characters; and together, they aim to create a play for the cultural festival in order to transform his normal school life into a sparkly one. [Written by MAL Rewrite]