Inner Voice: All Heroines Hear My Inner Voice - Chapter 12: Sona: I will win and you will be mine

I was transmigrated into a webtoon based on an alternate history of a shitty empire.‘I will overthrow this country with my own hands.’And the answer I arrived at upon experiencing it was ‘Coup D’état’.

A good-for-nothing man married a beautiful girl but was kicked off the bed on the wedding night. Furiously, he wrote a bill of divorce and ran away.
He was schemed a car accident in which he nearly lost his life. However, it turned out to be a blessing. He swallowed the soul that passed through the outer world, thus obtained superb medical skills and martial arts.
Later on, with the silver needles and invincible martial arts, he embarked on the road of counterattacks and was committed to his great dreams.

- Description from Novelupdates

Orlax Tirshtain is the villain in the global game [Unification of Empires]. The tyrannical, cold-blooded emperor is a man who slaughtered his own family with his own hands and ascended the throne with their blood—a power-obsessed madman. Despite five years having passed since the game’s release, no one has been able to defeat this lunatic. So, how the hell did I become this damned?????

Liola—the best assassin in his world—has vowed to kill no more. He was being chased by an assassination organization when he accidentally dropped into a parallel universe: through a dimensional gate and into poor teenager Kaiser’s apartment. Instead of going to the government shelter for lost dimensional travelers, Liola and Kaiser wind up going to school together.

Liola has been trying his best to live the life of an ordinary person, but after certain things happen one after the other, he begins to realize that being an ordinary person could be harder than being an assassin.