Cavalier of the Abyss

The mystical world of Chaos brings in a new protagonist, the rash revenge-driven undead named Xix against the brutal Immortal Regis of Chaos, Nex, who was once known as Jae Hyuk. Meanwhile various factions of the Regis' court and outside forces seem to be attempting to moves around the same time as Xix attempts assassinating Nex. (Source: TV Tropes, edited)