Majin Ou Kakusei

Nagarejima Narumitsu is the strongest player in a next-generation VR game, known by his in-game alias "Demon King." However, in real life, he's a high school student who gets bullied. One day, when he starts playing the game, he suddenly loses consciousness. When he wakes up, he discovers that the power of the "Demon King" has manifested in his real body! Original Webtoon