Grimm Otogi is a descendant of the Grimm Brothers, authors of the well known Grimms' Fairytales. Upon picking up a mysterious book he discovers in his house, Otogi is attacked by a demon.

He soon learns that the Grimm brothers vowed to sacrifice the lives of their descendants in exchange for the fairytales, forcing Otogi to defeat the demons from these cruel and twisted stories if he wishes to survive.