Plot
D.Gray-man follows the adventures of 15-year-old Allen Walker, whose left arm can transform into a monstrous claw and destroy Akuma (Japanese for 'demon'), evolving machines created by the Millennium Earl to help him destroy humanity. As ordered by his master, General Cross Marian, Allen becomes an Exorcist, one of the people who can destroy Akuma for the Black Order, an organization attempting to stop the Earl. With his left eye, Allen can detect disguised Akuma, making him a powerful asset for the Order. He is sent to recover pieces of Innocence, a substance giving the Exorcists the ability to destroy Akuma. The Earl decides to call together the Noah Family, superhuman descendants of Noah, who can destroy Innocence. Both sides start the search for the Heart, the most powerful piece of Innocence, which will ensure victory for the side that finds it.
In his search, the Earl begins killing the Generals, the Order's most powerful Exorcists. In order to protect them, the Order attempts to bring the Generals back to their headquarters. Allen and three other Exorcists are sent to find the missing General Cross, but Allen and Lenalee Lee are nearly killed during the mission. They are saved by their Innocence, causing the Earl, Bookman and Bookman's apprentice Lavi, who are chronicling the war, to believe one of them possesses the Great Heart. Meanwhile, the Order learns that Allen is to succeed Nea Walker, the 14th Noah, who was killed for betraying the Earl. This leads the Order to suspect that Allen might betray them, and he is eventually confined. The Noah frees Allen to rescue him from the Apocryphos, a sentient Innocence that guards the Heart, causing the Order to revoke Allen's rights as an Exorcist and treat him as a Noah.