MTL - Escape From Konoha - v6 Chapter 218 reality

When entire star systems begin vanishing without a trace, the shadow agency NEXUS turns to its last resort - Eric Blackmoor, a disgraced ex-agent and multiversal genius buried in guilt, alcohol, and exile. Once hailed as the mind that could solve anything, Eric is now infamous for an invention that annihilated a planet and billions of lives.

Transform into Divine Dragon and dominate the world!
He is the only Divine Dragon in the sea who founded an underwater Dragon Palace.
With Crawfish Soldiers and Crab Generals as his followers, wild sharks and gigantic octopuses as his subordinates, he is the dragon that rules the city.

- Description from Novelupdates

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.

It was in the year 2800 of the Midgard calendar. Back then, there was a Overlord who once reigned supreme and had reached the very brink of subduing the world.