Chronicles of the Heavenly Demon - Chapter 1: Woon Seong

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.

- Description from Novelupdates

(Female disguised as a man) Accidentally transmigrating into Long Aotian’s male novels is not scary, what is scary is transmigrating into a villainous little boss who will be tortured and killed by the male lead! ! Jiang Ru decided to cling to the male lead and change his fate. However, the hero is too sick and delicate, what should she do if she still feels that she can’t survive? ! Of course, thirty-six strategies are the best way to escape! Jiang Rudong hid in Tibet, fearing that the male protagonist would take him back and execute him Ling Chi, but on the way he heard that this sick and delicate king had a white moonlight who loved him to death… Hey, wait! Why is this Bai Yueguang… the same name as her? ! ! ! One day later, Jiang Ru realized that those who came out to mess around… always had to pay off their debts with their own bodies.

- Description from novelbuddy

Kawaki, who was born in the dragon vein of a planet (Altana), first met Umibozu who was traveling in the universe, and his girlfriend, Kouka.Later, he came to Earth by accident and met the teacher who affected his life —Yoshida Shouyou.He also met a group of friends. The most conspicuous among the group of friends is a fool with silver hair and naturally curly hair, a short man with purple hair, and a little devil whose catchphrase is “Not Zura, it's Katsura!”Gintama Doujin, not transmigration.