Diego is a teenage boy from a renowned vampire family in ancient mythology, when gods were still allowed to intervene in the world. Diego possesses eyes that can manipulate blood and his body to achieve twelve magic circles. An achievement unprecedented in history, as generally, no creature can attain more than ten magic circles except for dragons. Even the strongest gods are only capable of reaching nine magic circles, which is why they were incited by Gilgamesh to kill Diego for defying the laws of nature. In the end, Diego was defeated in his battle against the "Nine Constellations." At the end of his life, Diego was unaware that he would be reincarnated thousands of years later. He swore to avenge the actions of the Nine Constellations and reveal the true nature of the gods.