Why So Fandom-Savvy?

[amphitritie]

On the back of a certain book (which you are all free to guess) is the usual rating and warning. However, this warning has a little something . . . unusual. See if you can find it

Comments

[c0ntrarywise]

I don't know what the book is D: Is it a book-book or something along the lines of a comic book or manga? I need hints~