One Piece: My Crew is from Other World - Chapter 16: Slave Ship

In a land where no magic is present. A land where the strong make the rules and the weak have to obey. A land filled with alluring treasures and beauty, yet also filled with unforeseen danger. Three years ago, Xiao Yan, who had shown talents none had seen in decades, suddenly lost everything. His powers, his reputation, and his promise to his mother. What sorcery has caused him to lose all of his powers? And why has his fiancee suddenly shown up?

Su Mu took the player panel.

Came to the game world 10,000 years in advance.

The most common talent for players has been drawn:

…immortality.

However…

Although longevity, level experience is locked, what should I do if I can’t upgrade and become stronger?

Only practice, practice, practice!

There is no time in the cave, and a thousand years have passed.

On his way out, he found…

The girl I rescued casually back then actually created a tribe for me? !

Become a tribal totem yourself? !

…

Five thousand years later, the first batch of beta players arrived.

They looked at the totem statue standing in the first tribe, and looked at each other…

“This is the system introduction, a very easy to kill level 1 boss?!”

- Description from novelbuddy

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 world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.