Kingdom of Zombie

Kingdom of Zombie (킹덤오브좀비) is a manhwa series by Nojeok. It was serialized in Comic Champ.

Plot
Twenty years after a zombie outbreak Van, a mischievous child, escapes from the house of his grandfather to watch a gladiatorial tournament. In his way, Van is asked to deliver a letter to his hero at the gates where the zombies are being held, but a mysterious man kills the guards and lets the zombies escape. Being attacked by the zombies Van shows to have powers and starts to counterattack them.