The famous Seven Mysteries that every school seems to have are a staple of Japanese urban legends. One of the most well-known of these tales is that of Hanako-san: the ghost of a young girl who haunts the school's bathrooms. Kamome Academy has its own version of Hanako-san's legend. Rumors claim that if one successfully manages to summon Hanako-san, she will grant her summoner any wish. Lured by the gossip, many people have tried to call upon her, yet every attempt has failed. However, when Nene Yashiro, a girl hoping for romantic fortune, dares to summon Hanako-san, she discovers that the rumored girl is actually a boy! After a series of unfortunate events involving Yashiro's romantic desires, she is unwillingly entangled in the world of the supernatural, becoming Hanako-kun's assistant. Soon, she finds out about Hanako-kun's lesser-known duty: maintaining the fragile balance between mortals and apparitions.

Jashin-chan is a demon who was summoned by Yurine Hanazono, a gothic looking girl. Unable to return home as the relevant spell was not included in the summoning grimoire, Jashin-chan resorts to violence to liberate herself from her earthly shackles. However, this is easier said than done, as Yurine is no weakling herself. She in fact possesses formidable physical power and uses it to massacre Jashin-chan in a variety of ways, be it shoving her arm in a blender, spreading her intestines across the room or even cooking her. Though these actions would be fatal to anyone without the ability to regenerate, Jashin-chan isn't exactly undeserving of this treatment. Stuck with each other, Yurine lets Jashin-chan live with her in exchange for work around the apartment, and this cohabitation results in situations where, more often than not, Jashin-chan ends up in pieces.