Black Corporation: Joseon - Chapter 245

The eldest daughter of the Li family is beautiful and sassy, ​​she took space materials to flee famine, and after going through many difficulties in war, disease and epidemic, she united with her family to regain the glory and harvested a beautiful boy.

- Description from novelbuddy

The apocalypse arrived, and Irving was betrayed and killed by his own girlfriend.After his rebirth, he was chosen by the Will of the Blue Star to be an internal beta tester of the Shelter Game, starting with a [Tenfold Drop Rate] and becoming a [Necromancer]!Ferocious and brutal exotic beasts are all tamed by him, gradually forming a powerful “Exotic Beast Legion” under his command!Building sanctuaries, hoarding supplies, upgrading outer walls, setting traps...Constructing the most powerful fortress in the apocalypse!“Since I have been given a second life, I will trample those who've betrayed me once under my feet!”...When the Dark Lord descended, Irving's shelter had become the strongest on the Blue Star!“You evil creatures, dare to covet Blue Star?”“Come on! Let me show you what true despair is...”“Remember, from now on, Blue Star is under my protection! Got it?”

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