xD blood on a paper is different from blood in real life/ movies isnt it? I know a kids book with gore in it. But as for the 18+ content, its not really 18+. theres maybe 2 quick lines in it, and thats it.
Ok then... It depends on whats in the story, if theres violence, nobody cares, but SSC(Strong Sexual Contact) or S(Sex), maybe some L(Language) and then it can get PG-13.