Fumi Kamiyain, a plain-looking first-year middle school student, sports black bobbed hair, thick round glasses, and a skirt that falls below the knees. Despite her modest appearance, she has an unexpected talent — she's a master at mahjong! But that's not all — it seems she gains a "secret pleasure" from playing...!? Set in a Japan where underage gambling has been legalized, this slightly dangerous mahjong girls’ comedy explores the lives of young girls whose brains have been burned by the thrills of gambling!