Defense Breaker

Jihun is pulled into Knight Defense, a game where he must lead the kingdom's knights against endless waves of monsters. Weighed down by the scars of his real life, Jihun chooses not to fight and turns his back on humanity. But as soon as he does, the system unveils a new path: the Monster Faction. Defense is over. It's now time for offense.

(Source: Webtoon Entertainment)