This is a really great anime only just finished it, going to look into manga because it is still ongoing. The Anime was pretty crazy with a dope ass plot.
The ending I was like oh shit how did that happen oh hell fuck worst ending ever, 5mins later I was like oh shit that was so fucking amazing how did it happen omg that was fucking wtf I don't understand thats amazing.
Was sick as fuck! Must watch it. Going to do a detailed review on my website later.
http://myanimelist.net/anime/19429/Akuma_no_Riddle