In a world where Hunters with supernatural powers battle monsters to protect humanity, Sung Jinwoo is known as the weakest Hunter. After barely surviving a deadly double dungeon, he is chosen by a mysterious System that allows him to level up—something no other Hunter can do. As Jinwoo gains strength, he embarks on a journey to uncover the secrets of the dungeons and his newfound powers. Eventually, he learns he has been chosen to become the Shadow Monarch, granting him control over the dead. Now, he must fight other Monarchs who seek to destroy humanity.