Nessiah

First appearing at Machina Bridge, Nessiah is one of Gulcasa's Five Dragon Generals as well as Gulcasa's main strategist. The two of them appear to be fairly close. The extras list his age as "unknown", but the official site states him to be nineteen years old, at least in appearance. Although he seems to be a loyal member of the Imperial Army, he betrays them after Gulcasa captures Yggdra, killing all his men and informing Milanor of where Gulcasa is taking Yggdra before killing himself. However, he appears again a few battlefields later to scold Milanor and the Royal Army for not moving quickly enough. Nessiah is actually a fallen angel, and the creator of the Gran Centurio. When he lived in Asgard, he went by the name "Aries", and was a pure-hearted idealist—so much so that he refused to fight demons, because he was a pacifist. Asgard hated him for his stance, and it eventually led to his downfall, which is implied to have been orchestrated by Hector (the villain of the overarching story of Dept Heaven). Blinded, stripped of his wings, and bound by the Chains of Conviction—which force him to exist eternally, without being able to age or die—Nessiah was cast down to Yggdra's world; as soon as he regained himself from the trauma, he gave the Gran Centurio to Yggdra's family, and whenever the human world became too peaceful, he provoked conflicts that turned into wars. It is revealed that it was he who seduced Nietzsche's sister into stealing the Undine race's most precious treasure: the Transmigragem, an artifact which allows the Undines to survive as a species. And, as if to close the deal on what he has done to their race, he was also the one who coaxed the Undines to slaughter humans by giving them a dubious claim that the blood of humans could be used to make an elixir that could prolong the lives of existing Undines when used; preserving their race in the process. Source: Yggdra Union wiki