Knight Under My Heart is a Manhwa about the main character being invited to test a new VR-MMORPG and ends up being trapped inside the game due to the devs being evil freaks and experimenting - or rather torturing newcomers. You can't get out unless you beat the area you're being simulated - which is, in this case, a battlefield where the main character is at the front lines. Being thrown into this new enviroment he finds himself dying countless of times being stuck at an endless loop. The developers want him to despair and beg for them to make him leave, but he does theopposite. He learns to fight and adapts, no matter how often he resets.

It's pacing is extremely slow but that's what makes it a good read. You're constantly kept on edge to see what happens next.
And since I believe this is the main part of the story, it makes sense for it to be slow.

Overall, read it. If don't like it - fine.