D.Gray-man

The Millennium Earl offers grieving people the impossible chance to bring back someone they lost, then traps the returned soul inside a weapon called an Akuma. Fighting those weapons is the Black Order, an organization of Exorcists who can synchronize with a mysterious substance known as Innocence.

Allen Walker arrives to join them after years of training under General Cross Marian. His left arm is an Anti-Akuma weapon, while a curse in his eye lets him see the human souls imprisoned inside the Earl's creations. That makes every battle personal: destroying an Akuma is also an act of release. As Allen forms bonds with other Exorcists and the Earl's Noah allies move openly against the Order, the struggle grows into a war over Innocence itself and the future of humanity.