Everyone Laughed at My Dad Until He Saved the World — Episode 10

Arthur, a mighty archmage who saved the world three centuries ago, conceals his true identity and works as a janitor at St. Grace Academy. His son Lucas regards him merely as a down-and-out alcoholic given to empty boasting and is frequently ashamed of him. As dark forces resurge, Arthur shields Lucas in secret. When the Void God emerges, Arthur's identity is revealed. Tempered by ordeals, Lucas matures, gains love and undertakes the mission of protecting the world.