Mira
She looked at the girl's determined face and looked away from the girl. "An Akuma." she said softly. "It was an Akuma. A creature made up of two or more human souls, a metal skeleton, and...Dark Matter." she thought a moment about losses of everyone and continued " By design they are forced to obey the Millennium Earl and the other Noahs, even against their will." she stopped for a moment to let it all sink in then continued, "Akuma are created when a living human in mourning over the loss of a loved one, makes a contract with the Earl to bring the soul of said lost loved one back.The Earl presents the living human with a skeleton of Dark Matter and has them call the departed soul of the loved one back, the soul then becoming trapped within the skeleton and forced to obey the Earl's will. Once trapped within the skeleton, the soul then "puts on" the body of the loved one who called it back, using their skin to move around in the human world in disguise.After the transformation is complete, the Akuma, now a Level 1, the soul of which is tormented and consumed by hate for the living world, goes around killing in order to grow." she said softly and sadly. She swallowed and closed her eyes. A breeze flew by. She looked at the girl and said "You" she waited a few moments "Are an exorcist."