D.Gray-man is the story of Allen Walker, who roams a fictional 19th century Earth in search of Innocence, a mysterious substance used to fight demons called akuma.

Allen has had his heart pierced and his Innocence pulverized by an assassin from the Clan of Noah. Allen is taken to the Asian branch of the Black Order to heal. He is keen to rejoin the battle, but he will not be able to fight again until he learns how to activate his Innocence and turn it into a weapon.