Toilet-bound Hanako-kun

Jibaku Shounen Hanako-kun (地縛少年 花子くん, lit. "Toilet-Bound Hanako-kun") is manga series written and illustrated by Iro Aida. It is serialized in GFantasy.

Plot
At Kamome Academy, rumors abound about the school's Seven Mysteries, one of which is Hanako-san. Said to occupy the third stall of the third floor girls' bathroom in the old school building, Hanako-san grants any wish when summoned. Nene Yashiro, an occult-loving high school girl who dreams of romance, ventures into this haunted bathroom... but the Hanako-san she meets there is nothing like she imagined! Kamome Academy's Hanako-san... is a boy!