Tensei Shitara Slime Datta Ken (WN) - Chapter 21 – A New Movement

The tale of Oliver.
An orphan boy from a Mine, in 19th century Europe, filled with Magic.

“Gu Hangshen! Your sister stole my man, and you helped her do it! Your whole family is rotten!”“Whatever my sister owes you, I'll compensate you.”“And what will you compensate me with?”“Me.”“...”Later, he not only gave himself up as compensation, but he also came with a clingy little bundle of joy...

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

While I was reading the first volume of “Danmachi,” I suddenly felt my cock grow. It grew so much that it started to hurt.Suddenly, my sperm gushed out. Before I could understand what was happening, I realized I was in a familiar place.