Ryuuk the Death Dragon a dragon that is summoned in order for Shadow Release: Demonic Rasengan to work. Ryuuk was only summoned once by Teru(on accident) and never summoned again it's a miracle Teru survived because only those with strong will and no intention to get revenge may summon Ryuuk and not be taken in by his evil.Apparently Ryuuk and its opposite Myou have gotten into many fights involving the classic themes good vs. evil or light vs. dark. Ryuuk has won 19 of the fights Myou has won 21 of them.He seems to fear Teru's brother Takeo Kagami for an unknown reason.Ryuuk's and Myou's power may be linked to the Infernal Sword's power.