Konoha's Medical Ninja: One Punch to beat up Madara - Chapter 387 - : Sengoku is furious, again!

My name is Lin Fan. I have crossed the border. I want to cultivate immortality, and my mana is boundless.

After the Calamity War, the final and most devastating conflict to decide who would claim the Divine Throne, Kael Medici stood as the last survivor.He had led armies, fought with unmatched ferocity, and performed legendary feats. Yet in the end, his fate was no different from the rest. He perished like all the others, the final casualty of the Great War, his hand just shy of the throne he so desperately desired.But when he thought it was over… his eyes snapped open.He had returned to his youth, his memories intact.The path to divinity is drenched in blood, and the battle for supremacy is merciless. Yet Kael has already endured this once. This time, failure is not an option.With the memories of his past life, dominating talent and and a mysterious power awakening within him... The preparations to reach the Divine Throne were complete.

I returned after 10 years.

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