The Hunter's Lively Wife - Chapter 3 - Idiot

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

A 29 year old civil employment exam student wakes up in a blank white room and meets a baby angel. This baby angel informs him that he died in his sleep due to heart disease like his father and grandfather. Remembering his mom and their last conversation he says that he will take on a series of life and death tests that the baby angel offers him. From this point on he must put his life on the line and fight in the stage called ‘Arena’. And Every time he clears a test he will gain abilities and weapons to increase his strength. All to clear the tests and get his life back. This is his story of his fights in the ‘Arena’.

Fear breaks the boundaries between dreams and reality, and it is impossible to tell which is reality and which is illusory. When the nightmare really comes, no one can be alone.

This is both a danger and an opportunity.

- Description from novelbuddy

Before going to college, an ordinary high school student went to celebrate and got drunk. When he woke up, he found himself in a completely different world. There was a big sect, the approaching sect entrance examination, a slum where his body’s previous owner lived, and a shared memory about a missing young girl.

When he got tangled in a fight with a few punks in this different world, he fell off a cliff and miraculously found himself still alive, with two more voices ringing inside his head. They were Sword Master and Saber Master. In the company of them, he continued to find out more about this whole new world. He took the sect entrance examination, entered the sect, met a strange man in black, and even participated in a major competition of the sect to have a chance to win over his peers!
In this whole new world, he was born again and got to explore the fantastic martial world!

- Description from Novelupdates