Superstar From Age 0 - Chapter 348:

A world where the [Demon King] was defeated by a [Hero] that came from another world. People carelessly forgot about their fear of the [Demon King] and of monsters, living in peace.

In a forgotten and run-down cave in the mountains, a new monster that should not have been born was given birth.

The monster’s name was the [Black Ooze]. It was nothing exceptional other than its black color, an ordinary slime.

However, this slime had the special characteristic of being able to take the abilities of the living things it swallowed. It preyed on an insect that had paralytic poison, as well as other animals. Following that, it attacked a human, obtaining his knowledge and [Desire].

Before long, the monster established its target as the female mage that came to explore the cave.

This world still wasn’t aware.

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.

In the year 2025, humans awakened with the ability to summon mighty beasts—capable of destroying terrains, breaking the laws of physics, and creating wonders limited only by one's imagination.But before these blessings came a curse.An alien face appeared from nowhere and threatened all life on the planet, leading to the greatest war in human history.In the aftermath, the human race and the alien race were forced into a shaky treaty that could be broken at any time.Years later, tests for summoning abilities began for the next generation. Those who awakened low-grade summoning would be thrown to the gutters, while those who awakened higher got to join great factions after graduating from the academy.Kairos Veyl, the blank, calculating student, pulled his hand from the massive crystal pillar and stared at the large beast before him.“This kid—he just got a LEGENDARY SUMMON.”A legendary summon? The greatest class of summoning. However, with this class came a risk one would have never guessed.