He’s Mine, No Objections Allowed - Chapter 30

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

The Great Thousand World. It is a place where numerous planes intersect, a place where many clans live and a place where a group of lords assemble. The Heavenly Sovereigns appear one by one from the Lower Planes and they will all display a legend that others would desire as they pursue the road of being a ruler in this boundless world.

In the Endless Fire Territory that the Flame Emperor controls, thousands of fire blazes through the heavens.

Inside the Martial Realm, the power of the Martial Ancestor frightens the heaven and the earth.

At the West Heaven Temple, the might of the Emperor of a Hundred Battles is absolute.

In the Northern Desolate Hill, a place filled with thousands of graves, the Immortal Owner rules the world.

A boy from the Northern Spiritual Realm comes out, riding on a Nine Netherworld Bird, as he charges into the brilliant and diverse world. Just who can rule over their destiny of their path on becoming a Great Ruler? In the Great Thousand World, many strive to become a Great Ruler.

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!

Dante was an ageless warlock who had been going from one battle to another for hundreds of years.Following a chaotic encounter with an evil god, Dante unintentionally activates a contract with a demon, thrusting him into the modern world.Resolved to live a peaceful life, his intentions are halted when he finds himself in the middle of a conflict among rival mafia factions—dabbling with the ominous demonic magic that he knows best.