MTL - 9 Heavenly Thunder Manual - Chapter 43 Life hanging 1 line

Death followed Achilles like a plague.Finding himself at his lowest point, he comes to realize how little value human life held as terrifying Advanced Humans and Evolutius Beasts waded across the Colonies of this world.About to lose the only remaining person close to him by falling into the jaws of an Evolutius Beast, a spark bloomed inside of him, and he saw a distinct blue panel appear before his eyes![Achilles Maxwell][Assimilation]:: -[Existence Corruption Value]:: 0%[Complexity]:: NegligibleA simple spark. And yet the changes it brought…were limitless!

The end of the world is coming, the world has undergone great changes, and everything has changed. Plants, animals, and even insects, as long as there are living things, have mutated.
Become more powerful, and even evolved supernatural abilities, such as chickens and ducks that can fly to the sky, such as cats and dogs that can breathe fire.
But only humans, without any obvious changes, seem to have fallen from the top of the food chain to the bottom of the food chain overnight.
Any creature that can open its mouth to eat can treat humans as food.
But fortunately, this world has not completely killed humans. Gradually, humans discovered that they had the ability to cultivate compatibility with other creatures.
As long as it has a high degree of compatibility with some powerful mutant creatures, it can be used for its own use to achieve the purpose of protecting itself.
Fang He is a person who is very compatible with mutant animals, but it is also because of his ability that he has changed from the strongest to the stupidest.
Fang He, who was reborn, said, “Hmph, this time…”

- Description from novelbuddy

With one touch of the stone, Tyron receives his Class and his life changes forever.In an instant his bright and promising future as the scion of two powerful Slayers is torn apart and he must make a decision.Will he allow his Class to be purged from his soul, or will he cling to it, abandon all that he knows, and rise to power?

With a marriage contract forcefully done, he married her, and all she could do was comply, and resent him deeply for that and for all the following misunderstandings they faced.
However, it was already too late when she understood she actually loved him.