City of Sin (Yanyu Jiangnan) - Vol 9 Chapter 130: Endless Energy Core

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

Betrayed and condemned to death by the very family he served, Vikir, the hound of the Baskervilles, refuses to accept his fate.

With eyes ablaze and canines sharpened, he vows vengeance against his former master, Hugo. No longer a mere loyal companion, Vikir becomes the hunter, determined to exact bloody revenge and reclaim his honor.

Nine soul pets, nine fetters.

A hall of robbery souls, a bizarre adventure.

I looked down at them and they called me by my name.

I look up to the sky and write my legend.

“My name is Xia Lin, and I am the Lord of the Soul of Myriad Tribulations!”

- Description from novelbuddy

Damien Julian is an 18-year-old loser, who has been bullied and mistreated his entire life, at home, he has to deal with his abusive father, and at school, he is constantly been bullied by delinquents, and to make things worse he is always looked down upon by his peers, till one day a mysterious screen appear before him as it said.

[The world has seen the lingering evil in your heart]

[Would you like to be one of the nine demon kings of this world]

[If so what are you willing to sacrifice?]

In the heat of the moment, Damien made a deal with the world, that he would give up everything he owns, or do anything it wants, and in exchange, he shall be reborn as a new Demon King, and what the world required from him as payment was.

[In exchange for power, become a slave of the world, and act as an anti-body for all eternity]

At that moment, Damien agreed, but little did Damien know, that becoming a slave to the world meant he has to be its immune system, what that entail is, that anything that threaten the world must be destroyed even if he has to wipe out humanity, to save it, or assassinate historical figures to bring fort balance or even manipulating events that can potentially end the world, to save the world, this is the story of a necessary evil, not the story of a hero who cares for others.