Jin Suho lost his mother as a child and decided to become a hunter as he sought revenge for her. He gave his life to training himself and finally became a B-rank hunter. Then one day, Suho meets a mysterious man at a Red Gate, which appeared by chance. The mysterious man who introduced himself as the Heavenly Demon revealed to Jin Suho that Suho was his descendant and that he requires Suho's body to deal with his rival, the Blood Demon.