Mistress Of The Evil Forest - Case 72: The holy country of Neveah: Dragon Slayer.

When I opened my eyes, I found myself in a game where heroes and villains prevailed. I was told I would be granted one wish if I clear the game. The protagonist, who received a growth cheat that allows you to steal his stats by killing an opponent. He kills villains to grow up, but for some reason people mistake him for a “dark hero.” [Story-oriented]

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

10 years ago, after “the Gate” that connected the real world with the monster world opened, some of the ordinary, everyday people received the power to hunt monsters within the Gate. They are known as “Hunters”. However, not all Hunters are powerful. My name is Sung Jin-Woo, an E-rank Hunter. I’m someone who has to risk his life in the lowliest of dungeons, the “World’s Weakest”. Having no skills whatsoever to display, I barely earned the required money by fighting in low-leveled dungeons… at least until I found a hidden dungeon with the hardest difficulty within the D-rank dungeons! In the end, as I was accepting death, I suddenly received a strange power, a quest log that only I could see, a secret to leveling up that only I know about! If I trained in accordance with my quests and hunted monsters, my level would rise. Changing from the weakest Hunter to the strongest S-rank Hunter!