Light of Arad: Forerunner

Jinseong streams the online action game Dungeon and Fighter for a living, and while assisting a ranger, he ends up doing exactly what the player warned him not to—helping him fight the boss. Little did Jinseong know that the ranger was a person sucked into the game world, and was now dead for failing his mission. Transported into the world of DNF to take responsibility, Jinseong must work his way through the quest line as a Dark Knight to stop the contamination from leading players astray and destroying the world of Arad. Will he make it through alive?

(Source: WEBTOON)