MTL - The Two Proud Sky Dragons’ Shura Fields - Chapter 53 discuss

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

Enigmatic hands, spectral frame, and one cunning strike just like the swing of the Grim Reaper. The Supreme Assassin takes on the mystical world, and how his legendary tales sets off, progressively ascending the altar to becoming the best.

- Description from Novelupdates

Fifty years ago, the world changed forever when Earth was mysteriously connected to the Primordial World, a reality that operates like a game.This world can only be entered by Awakeners—people who have awakened with special powers. However, out of fifteen billion humans, only one million have this privilege.Enzo, a poor young man with no connection to the Primordial World, should have had no chance of becoming an Awakener.However, against all odds, he awakens... and more than that, he gains an innate skill unheard of before—the ability to make skills with only his imagination.In a world where power determines everything, how will a nameless young man carve his own path?

Just like how everyone adored heroes in their childhood, a certain young man adored those powers hidden in shadows. After hiding his strength and living the mediocre life of a mob character by day while undergoing frenzied training by night, he finally reincarnates into a different world and gains ultimate power. The young man who is only playing at being a power in the shadows, his misunderstanding subordinates, and a giant organization in the shadows that gets trampled…. This is the story of a young boy who had adored powers in shadows possibly eventually reigning over the world of shadows in another world.

The undisputed greatest doctor in Korea, Baek Gang Hyuk.