If this were a game, the community would mock Jin-Woo as a boosted stat monkey, relying solely on gear and levels to dumpster newbies. This revolves back to my dislike of his progression system. He's not smarter or more skilled than his opponents. He overpowers through sheer numbers in more ways than one. He wins because his dagger mastery raises his DPS. And the fact that his ability to level is his only defining trait makes him incredibly one-dimensional. If other characters leveled, you'd realize how stale of a character our protagonist is. There's no good way to describe his personality because he's nice and hollow for the self-insert. He grows a few inches, sculpts a nice jawline, and picks up hot nurses never mentioned again. You could say he cares about his friend and mom and sister, but that's 99% of good people. But I digress, as my point was about his strength. Powerful characters are actually fine. I don't hate them. But they require equally powerful adversaries to warrant it, or else they're just bullying children. Once again, he's an empty shell, and this leads me to the next issue.
Jin-Woo is the director, producer, actor, make-up artist, and so on scrolling down at a movie's conclusion. Some may like this, but I find it a shame to take all the credit. Hopefully few wanted substantial, lasting relationships in the novel, whether it be friendship or romance. No one is worth his time, and whatever connection he has with someone is weak and a passing paragraph. Even if he cares a lot about a character, should we, the reader, care? He can't let another star shine in the spotlight, and as such, the supporting cast have personalities and relevance made of cardboard because author-kun lets Jin-Woo steal the show. He is the protagonist, yes, but he holds too many cards for me to be concerned about his wellbeing, and those cards are as flat as he is.