Rebirth in One Piece as Deputy Captain - Chapter 12 Strange Small Town

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

“Even if this universe is truly nothing more than a brutal bloody shadowy forest, we Cultivators will burn all that we have just to give off a single weak flickering spark in the darkness!

No matter how weak each spark is, how short-lived, how small… As long as the sparks flow unabated, then one day one of those sparks will light some tinder, and that tinder shall light some fallen branches, and those branches shall set ablaze each and every last tree of the forest!

In the end, even the smallest sparks will eventually set the shadowy forest ablaze, and illuminate the whole world!”

In a world teeming with cultivators, Li Yao, who makes his living collecting scrap metal, encounters the soul of a titan powerhouse from forty thousand years in the past.

- Description from novelupdates

Crossing to One Piece world, he became Roger’s younger brother.

Unexpectedly, Gol-D-Roger who was in his fifties had a teenage brother. But he was so weak.

Fortunately, at the age of sixteen, he actually found himself with a possession soul system.

He had attached to the master IP man, also to the White Phoenix and to Ge Nie with his strong ability of the Hundred Step Flying Sword.

If you think that he can only Purchase these? Then you’re wrong!

Pain, Itachi, Ichigo Kurosaki, as long as there is money, any soul can be Purchased.

- Description from Novelupdates

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