Allen Walker a 16-year old kid whose left arm can transform into a monstrous claw and destroy Akuma, evolving machines created by The Earl of Millennium to help him destroy humanity. He got trained by one of the Black Order generals Cross Marian which he told him that he can become an Exorcist, humans who can destroy Akuma, for the Black Order, an organization attempting to stop the Earl. Allen became a powerful asset for the organization because he can detect disguised Akuma's with his Cursed Eye. The Earl decided to gather the Noah Family superhuman descendants of Noah who can destroy Innocence. Both side start to make their search for the Heart the most powerful piece of Innocence that will ensure victory to the side that finds it. As soon, the Order finds out that Allen is to succeed Nea Walker a Noah that betrayed and was killed by the Earl, as the 14th Noah. This leads the Order to suspect that Allen might betray them, and he is eventually confined. The Noah frees him to rescue Allen 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.