MTL - The Whole World is Licking Me and My Ex-girlfriend’s CP - Chapter 65 explain

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

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

After an ultimate battle against the King of Hell Lucifer, Asmodeus, the Vampire Emperor, has fallen. Although he lost, he died without regrets and with a smile, prideful that he had managed to corner the King of Hell himself to such an extent.

However, due to a sick twist of fate, Lucifer himself decided to reincarnate him into the feeble body of a human child named Blake, desiring a rematch in the future!

Now, given a new opportunity at life, Blake will use every possible way to grow stronger and protect his new family in a turbulent world where people can summon spirits to fight and develop their magical powers.

Armed with only a Grimoire, he’ll slowly summon all of his previous life subordinates, who are all powerful Vampires, and rise to the top while fighting the ever-growing menace of the Demon Towers.

Accompany Blake through a journey filled with excitement and growth and experience the rise of the Vampire Emperor. A new Era of Blood is about to begin.

When Ye Mo suddenly woke up, he realized that everything around him seemed to have changed: He has been transmigrated into the modern Earth where spiritual energy is scarce. His pretty master from his former world was nowhere to be seen. Most importantly, he found himself in the body of a young man who has been abandoned by his clan for an embarrassing reason…

- Description from Novelupdates