Allen Walker is not your average fifteen-year-old boy - he is an exorcist and a member of the Black Order, an organization charged by the Church with the elimination of Akuma. The Akuma are the minions of The Millenium Earl - an evil demon-like entity intending to cleanse the world by destroying the entire human race in the manner of Noah's great flood. Allen and the other exorcists are special people who are compatible with a substance named Innocence, which allows them to form Anti-Akuma weapons; and as such Exorcists are the only ones capable of fighting the Akuma. Allen and his friends must battle to save humanity from the Akuma and Earl's evil plans.
These both manga is about demon killing and one trully powerfull enemy. Good reads indeed. ANd both manga have main character that is willing to sacrifice anything for beating one main enemy.