I watched this anime because one of my buddies recommended it to me on Xbox. I started it on Crunchyroll and marathoned the entire thing. When I was down at AX this year I decided to buy Blue Exorcist Vol. 1 for 8 bucks. And I have to say that the manga is very on par with the anime however it extends out further than the anime. It's a good read and Kazue also put some detailed information in the back of the book about Rin, Yukio, Mephisto, Shiro, Sheimi etc. Its a good read and I highly reccomend it. If you dont want to read the manga watch the anime. If you have seen the anime, read the manga if you want to know what happens after Rin and Yukio destroy Gehnna's Gate.