Killia is the main character of Disgaea 5: Alliance of Vengeance. He is a young demon that intends to take revenge against Void Dark, sharing a deep fate with him. He dislikes making allies and fighting together with others. Burning calories furiously fast, he needs to eat often and will, anytime and anywhere, whenever the opportunity presents itself.
As it turns out, Killia is actually the former Tyrant Overlord Killidia, the once strongest Overlord in all of the Netherworlds. After being defeated by Goldion, he ends up becoming one of his apprentices. It was Void Dark accidentally killing Liezerota that triggered Killia wanting to get revenge against him. He consumes a lot of food so that Killidia doesn't overtake his body, causing wanton destruction.
