Castle of Black Iron - Chapter 2012 - The Agreement between Zhang Tie and Demon Overlord

He became a teacher at the best magic academy in the empire.
….For being mistaken for someone else.

Amidst a disaster, an orphan contracts a sickness.

In his waking hours, he is tormented by his ailment, but when he slumbers, there is infinite darkness.

One day, when he was five years old, a strange Fate Trickster appeared in his dreams. Ten years later, he dreams of becoming a lord. To do so, he takes a chance to trade his fate!

That day, Wang Zhong once again stood at the gates of the Tianjing Heroic Soul Academy. He was about to start a brand new life.

- Description from Novelupdates

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

Shiro Sakamaki was reborn into a new world with one simple goal: to live a peaceful, luxurious life free from drama.But when he transfers to a prestigious high school in Tokyo, he quickly discovers that his new reality is anything but ordinary. The city is a strange mix of supernatural forces, ghostly phenomena, and events that feel like they’ve jumped straight out of an anime.Before long, bizarre occurrences follow him everywhere, along with a series of beautiful, mysterious girls—from the arrogant, blonde twin-tailed exorcist, to the mysterious quintuplet sisters, to a passerby heroine with hidden powers.As Shiro gets tangled in the supernatural chaos, he realizes he’s at the center of something far darker. Cursed relics begin to surface, and Ancient, Evil Outer Gods—whose very presence bends reality—start to stir.Now, Shiro must figure out why he’s caught in this web of strange occurrences while trying to survive school and the surreal new world he’s been thrust into.