Yousei Kaizoku is a pirate. A fairy pirate, at that. He used to work for the Pirate King Kuro Tori and the Blue Dragons, but he was later captured by the Yamatians who brainwashed him and forced him to work as the Admiral of the Yamatian Navy. He formed the Black Hunters and opposed the Grand Alliance at every turn during the Great War. When Yamato lost the war, Yousei managed to overcome his mental conditioning. He took his remaining Black Hunters with him and moved to fight against the demons and save captives in Southern Yamato. Kaizoku and the Black Hunters witnessed the Sinking of Khrima, and fought in various battles since, culminating in a decisive clash against demons along with other rebel forces in the Battle of Hephaisteion.