Invincible! This person has lived for a billion years - Chapter 54 Act according to my cues.

The Revered Master, Yu Yan, known as the number one in the cultivation world, waited for sixteen thousand years, and finally took in a disciple. He taught her carefully, and took care of her diligently. He watched her as she slowly grew stronger as she comprehended the laws, and just as she was about to soar into prominence… she died!

Freshly turned eighteen, John Newman, a helpless nerd, suddenly gets video game abilities granted to him. A mysterious higher power, a secret Abyss of magic beneath the surface of the normal world, mages, martial artists, eroticism, tragedy and a harem of hot girls awaits.

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

Huang Dan’s pain nerve is innately different from the ordinary people. A little tore in his skin can cause him to sweat all over his body painfully to the point of him unable to make a word out.

Somehow, he began to cross world, following Mr. System to do the tasks…

In the first world, Huang Dan realizes what it means to die painfully and to live to die again.

TL’s summary:
MC suddenly transmigrated and is bind to a system, requiring him to solve mysteries. Born with a higher degree of pain sensitivity, he met different people in the different worlds and learns what kind of emotion smiling is.

- Description from Novelupdates