From the introduction:
The Nine Hells are a very bad place, full of pain and torment and devils! We must never forget about the devils. The devils are the rulers of the Nine Hells and live by a strict hierarchy of dominance and tyranny. Weak devils are ruled by the strong, who are, in turn, ruled by the strongest devils of all: the arch-devils. As we take out tour through the Nine Hells, we will find out more about these powerful fiends and their wicked plans for the mortal world!
In addition to the coloring book pages, the item includes game statistics, etc., much like a more-traditional bestiary.