The man is a minor character of The Promised Neverland. He is a former ally of Julius Ratri, who due to the latter's sacrifice to end the war between demons and humans, became one of humanities' first cattle.
Nearly a thousand years ago, he was a leader of an unknown country who was caught up in a war between the humans and demons; losing his father, brother and many soldiers in the process. At some point, he met five other human leaders on the battlefield, including Julius Ratri, and they all became trusted companions, putting aside nations and races to fight together. One night after suffering countless causalities, the six leaders discussed about how to end the war. Julius suddenly proposed to the idea about offering up a portion of humans to the demons, but the man and the other four leaders were against this, deeming that it was possible to end the war without any human getting eaten.
A few days later, Julius once again brought up his previous proposal and wanted his allies to reconsider it; sick and tired of continuously having to sacrifice people. His allies refused once again; not only to save innocent humans, but because they didn't want Julius to suffer on his own and carry all of his burdens by himself. Julius, however, was dissatisfied by their answers, and brought several demons to their hideout, revealing that he had already made a deal with . He betrayed his allies to achieve peace between the worlds, in which the black-haired man and his four other allies were devoured by the demons, and in the process, became humanities' first cattle.
He was a slim adult man with an average build and height who had sharp, dark-colored eyes. He had long, straight, black hair which he wore in a ponytail at the back. He wore his fringe in a slicked-back middle-part with two long locks of hair framing his face. Additionally, he had some sort of mark on his right cheek. Overall, his hair and facial features resemble those of Ray's.
He was a level-headed and rational man who was both moved by his allies' idealism, but also acknowledged that Julius made several logical points in his proposal to sacrifice a portion of humans. Nevertheless, he still had strong morals and deemed the proposal as a rational judgment that was sorely lacking in morality. He also appeared to be a loyal man with a deep sense of responsibility; fighting to protect his people and being devastated over the deaths of his family and soldiers.