In the MCU/Marvel with the Omnitrix/Ultimatrix - Chapter 27: I want big green to be my friend

Benedict was transported to a world of cultivation and awakened the Invincible Domain system. Within this domain, he was invincible!

The consciousness of a Great Magus suddenly returned to his original body on earth, just before he transmigrated into the magic world.

Nothing has changed, it's still the same earth.

However, when he looked at earth once more as a former great magus, he discovered earth was not as simple as he knew it to be.

Hidden magus, legendary races such as vampires and werewolves, they do exist, ruling the world through the shadows.

Faced with a former great magus, who possessed as many spells as libraries, would the earth that had been ruled by a few people be able to remain calm?

However, he did not know that he was not raising just a harmless pet, but a biological weapon secretly made by the government… a real monster.

As a former librarian, Rand felt that he had been living an ordinary life, the one that he had reclaimed unconsciously every single day.

Recently, he has been a little upset because the pet fish he accidently brought home to raised seems to have undergo some strange changes

Well, it turned into a merman.

- Description from Novelupdates

Liam who was born from a once prestigious household was found out to be a genuis of magic, genuis that appeared only once in a minnelium but as he reached the age of awakening the system it was found out that he was no different than a normal human although he had legendary skills they all appeared to be locked.Now living with his single mother who was struggling financially Liam could not bear to see his beloved mother in such a state.One day while on his way to town he mistakingly entered a dungeon and that marked the beginning of his new life...