Surprise! Tyrant's Little Crybaby Went on a Killing Spree After Being Reborn - Chapter 12

It was supposed to be a perfect deal in which both parties got what they needed. However, after the child was born, he tore up the agreement with discontent and told her, “Who said that we’d only have one child? I want twins! Twin brother and sister! You’ll continue giving birth to more children until you bore me a pair of twins!”

Damian, a Centurion of the Punishment Unit of the Baroque Kingdom. “Damn it.” Just once. If I were given just one more chance… ‘I would have truly conquered the battlefield with these guys.’ At the age of 30, he closed his eyes on a nameless battlefield. But when he opened them, he found himself back 17 years in the past. And this time, he had a perfectly functioning mana core that could wield magic. ‘This time.’ I will rise higher than anyone else. I won’t be swept away by the turbulent times. ‘I will conquer.’ Damian, who has returned to the past, wields his spear toward the world.

The little handsome son-in-law passed through a world as waste material and the husband of a wealthy family. But because of his lacking aptitude, the wealthy family had driven him out. So he worked hard and found a more powerful family’s thighs to hold onto. Soon enough, he became the strongest son-in-law and husband in history.

In this world, it was impossible to practice martial arts. It was futile so he might as well take advantage of his wife’s thighs and maintain a comfortable and leisure lifestyle.

He’ll train his wife to become the strongest and best person in the world.

“Whoever dares to provoke me, let my wife kill you!”

- Description from Novelupdates

In this world, orphans or just anyone without any hope for this world can apply to become a “walking target”. Their sole purpose is to be a practicing dummy for the students of the sect who train to become “Demon Hunters”. These students need “walking targets” to test their training on living, walking beings of flesh and blood.
In exchange, they will be provided with food & shelter.
Their existence value is lower than a slave, but if they manage to survive a few years they can receive a life long pension.

Xiao Han is such a “walking target”. One time he witnessed a powerful Demon Hunter disposing a demon. When the demon died, a fragment of the demon that managed to escape entered Xiao Han’s heart. No one saw that, and even Xiao Han himself only felt some discomfort for an instant.

But that thing in his heart soon gave Xiao Han visions, and the first one is of a cultivation method which allows Xiao Han to absorb damage to enhance his body. A perfect cultivation method for a “walking target”.

- Description from Novelupdates