B is For Boss

A young boy found himself transported into the world inside an RPG video game where he stumbled upon a lair of monsters and encountered the most powerful boss in the game.
The demon took him in like a son, giving him a new name: Qi Wu, before subjecting him to an endless gauntlet of grueling training.
Eventually, he became strong enough for the demon to send him on a mission.
But it was during this mission when Qi Wu would discover a shocking revelation...