Kirsch, a boy who works with Sister Grimm, who works as a demon teacher in Erebus City, a city where monsters and strange phenomena occur frequently. From the Infectious Zombie Incident six months ago, Grimm and Kirsch conclude a contract and put themselves in the devil business with each other as a partner. Vampires, monsters, monsters from other worlds, and all kinds of bizarre monsters are defeated, and the exciting violence action begins here