Shortly after AdmiralZhao's siege of the Northern Water Tribe, Hiryu was kidnapped from his village by one of Lian's machines. Master Wei called upon AvatarAang to help save him and sent him out to find clues that would indicate who or what had caused Hiryu's sudden disappearance. However, after PrinceZuko raided the village, Master Wei informed Aang that Hiryu was likely dead.
Hiryu did not make an actual appearance until the last boss and level of the game. Despite him controlling Lian's machine, he later walked out of her fortress with Team Avatar.