In Kamome Academy, there are seven mysteries. The seventh, and most famous one of all, is "Hanako-san of the Toilet", a ghost girl said to reside in the third stall of the girls' bathroom on the third floor, with the ability to grant a single wish for the appropriate price. Yashiro Nene, a first-year high school student, approaches the cubicle intending to wish for a happy romance with her crush and popular senior student Teru Minamoto, only to realise that the "Hanako-san" of the rumours is actually a boy! Yashiro and Hanako work together, consulting tips and tricks from a self-help book, only to fail every time...