I'm The Devil - Chapter 75: Satanael Arrives in Koguryŏ Realm

One day, a handsome young man died in a car accident. He suddenly wakes up and find himself in an unfamiliar place, but what surprised him most is that he is taking over someone else’s body.

A mysterious natural phenomenon caused the Earth to be plunged into darkness. The world turned into an endless bloody chaos and mankind is on the brink of extinction…

Wang Zhong arrived in an alternate world and became embroiled in this world's global war.What he gained was a cheat, akin to a real-time strategy game's overhead perspective, and he could even see through the eyes of his subordinates' units!So, he decisively started micro-managing, “Shift the machine gun position five centimeters to the left! Place the anti-tank cannon in the forest on the right!”Three years passed in this manner, and Wang Zhong looked at the marshal's baton in his hand, then at the double-headed eagle flag behind the emperor's envoy.“In my hometown, there's an old saying, 'Princes and generals, are they not sprung from the masses?' Envoy, do you know of it?”

In the endless Universe is eight primordial laws. Each of the eight laws have been fused with a supreme expert, but unbeknownst to everyone, there is a ninth law in the universe. It tears open the Primordial Chaos and is beyond reach.

Di Jiu—whose name is a homophone for ‘ninth’—is the ungifted son of a powerful Di family clan in the Ji Nation as he lacks martial roots. Unwilling to resign to his fate, he practices medicine, hoping to one day cure himself.

- Description from Novelupdates