7th Demon Prince Jilbagias' Chronicle of Demon Kingdom Toppling - Chapter 89.2 - Price of Sin

Following a brutal and tortured death, a former assassin, known only by his codename Kuro, is given the opportunity to reincarnate in another world, a world with magic and monsters. Armed with an unrivaled healing factor and an inhumane pain threshold, Kuro opts to go for a reckless direct approach in this world instead of a stealthy and cautious one, and as a result, slowly gains attention bit by bit.

Having previously been a loner in his old life, he interacts and befriends people for the first time in his existence, however, his blunt nature also sees him making just as many enemies, both big and small. By combining his old assassin skills with the magic powers of this world, along with his high resistance to pain and rapid regeneration, he doesn't take long to establish himself as a formidable force in this world.

Initially, Kuro only faces minor threats, like weaker monsters and bandits. But before too long, the threats slowly but surely become more and more severe…from Zombies to a bloodthirsty empire to Vampires and Demons, and even divine beings…however, as the enemies he faces grow stronger, so does Kuro, gaining rare powers that have never or rarely ever been seen in this world…

What if your own father and his mistress were behind your mother’s death? What if you were about to be sold off to a scumbag?

What would you do? In the nick of time, a tall, rich, & handsome guy descended from the sky and came to her rescue with a piece of contract.

Xin Qing glowered at the man before her. At first, she had thought of him as her Prince Charming, in the end, he turned out to be an evil demon.

“You’re not allowed to go. You can only marry me!” the man said viciously to the woman who was about to leave.

Xin Qing sneered. “Isn’t the ancestral behest the only reason you’re keeping me around? I’m just your tool.”

He said, “Who told you that?”, his eyes filled with profound emotion.

“You’re the mother of my child!”

- Description from Novelupdates

After getting forcefully reincarnated into a world of an otome game he has no clue about, the protagonist is then killed and brought back to life by the prideful villainess with one desire.

To rule the world.

As the ruthless girl’s Eternal Servant, how will he dodge the fate that the game system has in store for him?