At Kamome Academy, the legend of the “Seventh Mystery” — known as Hanako‑kun — persists: a ghost said to haunt a school bathroom and grant wishes. But when first‑year student Nene Yashiro summons him hoping for romantic success, she discovers Hanako‑kun is actually a boy (not the traditional ghostly girl of the legend). Hanako‑kun reveals his true role: he helps maintain the delicate balance between the living students and the various supernatural entities (yōkai, apparitions) that inhabit the school grounds. Nene becomes his assistant, helping him fulfill his duties — even when those duties extend beyond just granting wishes.