Hidden from society, there exists a realm that is made of the connective human consciousness, the Hollow World. This world is one where entities feed off of, and where a secret society of people named the "Bedeviled" reside. The Bedeviled are a ruthless society that causes chaos in this realm to benefit themselves, causing mass destruction to appear in the Overworld.

To prevent this information from reaching citizens, each government established a military branch called "The Cognitive Hollow World Enforcement Bureau," a unit dedicated to eliminating Bedeviled from the Hollow World. Devils are like snakes, and awfully careful, even hiding their identities among themselves. Simon Crest, a man who's considered a prodigy by most of the bureau, is thrust into action immediately and finds himself blurring the lines between enemy and ally.