Slave Harem in the Labyrinth of the Other World - 016 – Demon Room

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

On the distant Tianxiu Planet, there exists a group of unusual and intelligent beings. They consist of neither children nor elders. They have neither birth nor real death. They are born into the world through an extremely special process and have managed to keep their fundamental memories of survival through their endless reincarnations.

They are the Tianxiu people.

For every Tianxiu person, if they find someone they like and want to bind as partners with each other — then they would have to go through a life or death Adult Ceremony. The winner of the ceremony will become the absolute dominant in this spousal relationship.

While the defeated one will be referred to as — Qizi.

- Description from Novelupdates

After a cataclysmic event called The Great Calamity, strange rifts began opening all around the world, giving entrance to places we never saw before, full of monstrous beings.We call them Nests.The world, then, gave birth to people with special abilities. Powers that allowed them to fight the beasts inside the Nests.Those who chose to raid the Nests and fight for mankind were called Wielders, and little by little, society came to get used to the perspective that magic had become an innate part of their lives.My name is Kurt, and I was a regular, a person with no special abilities at all.I didn't awaken when I turned sixteen, when usually a person should awaken their powers.After being kicked from home and living years in the streets, I was caught in a trap engineered by my brother, so that my father, Octavius, could kill me.But I won't stay dead.I earned a system and went back in time.And they'll learn the true meaning of vengeance!