MTL - Night of the Nine-Tails, I Punch the Tailed Beast Ball - Chapter 473 living puppet

At age 5, Amon unlocks the unique «Fury» genetics and is what caused his behavior to change.

After living with his grandparents for 11 years he learned to behave. For reasons he can’t know, his grandparents faked their deaths, and now he needed to move.

Now he would have to face a new challenge which was to live with his mother and stepfather and two twin sisters not linked by blood and go to school.

This is a story of a little man who walks forward silently, in awe, and strives to chase his dream.

- Description from novelbuddy

On modern-day Earth, An Lin seems to have been abandoned by God.
When his father suddenly disappears, An Lin is left with his father’s immense debt, putting his life at risk.
After being forced to a rooftop by his pursuing creditors, An Lin is unexpectedly swept off his feet and brought to the ground safely.

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.