Academy's Reincarnated Hero

Joonwu Kim, the 1st generation hunter, a hero, and founder of the subjugation system and code against monsters, finally defeats Gigantiana at Black Tomb Dungeon, but it costs his life. As he lay dying, Gigantiana softly whispered, "I will be resurrected in 42 years and bring destruction to this world." 42 years later, Joonwu reincarnates into the body of another person, namesake Joonwu Kim, who has a young teenage physique. A moment to rejoice for a new peaceful world is short-lived. Joonwu becomes distraught, witnessing the subjugation system and Hunter's Law that he and his cohorts had built on their bloodshed and sacrifices in disorder. With this state, Gigantiana's resurrection will bring devastation to this world. (Source: Naver, translated)