Book of Simon

refers to a book containing knowledge about magic. They are considered to be powerful tools with esoteric knoweldge and powerful magic spells written in them.

It is harmful to all who dare read its contents, although, currently, only Kyle and is immune to the debihiltating effects of the grimoires, and with his perfect memory, allows them to serve as the vessel of the Book of Simon. However, suspicions rise that he would rebel and become a Majin.

Principles
As stated, original grimoires are harmful as reading its contents would drive a human into insanity, and are even harmful to those that are trained to handle them.

According to the index, what is written inside of a grimoire is of a different world, and contradicts common sense, a knowledge that is far too alien to be safely comprehensible to any normal human. The knowledge that a grimoire possesses is "poisonous" in the sense that it is too "pure" for the human mind to handle and must be "watered down" – i.e. written in such a way that many of its meanings are obscured – in order for people to be able to read it without their minds being destroyed. Once a human is stained with the poison that is the contents of a grimoire, even inquisitors cannot remove the poison from the mind even after five years of baptism.