Mana Walker is Allen's foster father. Allen was originally abandoned by his biological parents due to his deformed left hand, which was caused by his Innocence. When Mana found Allen, he decided to adopt him. Over time, Allen formed a very strong bond with Mana. It is unclear how Mana died, though in the anime, a scene of an overturned coach was shown. For Allen, Mana was like his father, so he mourned for him. The Millennium Earl approached a grieving Allen after Mana's death and offered to bring him back to life. Allen, who had loved Mana, accepted the offer. Mana was then turned into an Akuma and, infuriated by Allen's actions, cursed him by cutting his left eye, leaving a pentacle marking, and giving him the ability to see Akuma with that eye. He was quickly destroyed by Allen's awakened anti-Akuma weapon. Before his Akuma form was destroyed, he told Allen that he loved him and thanked Allen for righting the wrong he had committed.
In chapter 219 of the manga, it is revealed that Mana is half of the Millennium Earl. At some point, the original Millennium Earl gave up on his mission and split into two, resulting in the birth of Mana and Nea. The two were raised by Katerine Eve Campbell, the former Earl's lover. When their Noah awakening occurred, Mana was embraced as the new Earl while Nea was rejected as an "extra" Noah not meant to exist. The two rejected their heritage, killed the other Noah, and went on the run. Eventually, Mana's Noah memory overpowered him, leading him to kill Nea in vengeance. Thirty years later, Mana regained consciousness with no memory of killing Nea or awakening as the Earl. He began traveling as a clown to hide from the Earl's golem suit, which was hunting him, and to find his missing brother. He found Allen one Christmas Eve while taking on a new contact and took him in as his assistant after Mana's partner, a dog also named Allen, was murdered. It was actually Allen's decision to start traveling with Mana as his caretaker after Allen accidentally broke Mana's mind when his Innocence awakened, rendering him demented.
