Global Reincarnation: Only I Know the Plot - Chapter 884:

Once through the pirates, Lu En became the son of Monkey d Dragon, a grandfather named Monkey d Karp, and an unreliable and neurotic younger brother named Luffy.

Fortunately, the ghost back system is activated!

The completion of the ghost back is 10%, and the training effect is increased by 100 times!

The completion of the ghost back is 20%, and the training effect is increased by 1000 times!

…

One day, Lu En, a ghost-backed master, appeared in front of Luffy who was shouting to go to sea, and made Luffy cry on the spot.

Luffy: “The pirates in the sea are all monsters like my brother? I don’t want to go out to sea!”

Garp: “For a long time, the two boys, Long and Luffy, with small arms and calves, I really doubt that they are not my sons and grandsons. Like Lu En, they are the grandsons of the old man!”

Warring States: “The strongest creature in the sea, land and air is Kaido? No, it’s Lu En!”

- Description from novelbuddy

A young boy genius, Suo Jia, is a water mage who dreams of being a warrior travelling the great and dangerous trade routes to find his lost father that set off on them before Suo Jia was born. Having to look after his sick mother, Suo Jia manages to find a way to solve all their problems, as well as make a name for himself. He gathers nobility, vast wealth, items of great power, knowledge lost to the ages, and exceptionally talented females around him as he plots and plans – preparing to set off on an epic journey that will go down in history as a new legend. However, will others that depend on his powers so much be willing to let him go on such a dangerous journey so easily?

- Description from Novelupdates

The King Of Assassins was a monster that reigned over the world of hitmen for long years. He was the absolute peak that no other being could reach. His name reached the ears of every powerhouse in the world and sent shivers through every human.

Yet, his legend came to an end suddenly when he died in unknown circumstances.

However, instead of disappearing forever, he was given another chance in another world by the goddess of reincarnation. It was the world of an old book that he read back in the time. A world where everything was possible, where humans could reach new heights that were impossible in his old life.

But, this place didn't seem to be normal as it carried a huge surprise that will make his journey seem all the more interesting.

The Goddess of reincarnation wasn't as holy as anyone would think. She was nothing but a twisted being who found a toy to play with. The goddess manipulated the world that he was going to and changed all the heroines into these twisted beings that fit her character. They were all now harboring this unhealthy obsession toward him and trying with all their powers to take him away for themselves.

With the revival of spiritual energy and the breakdown of the order of species, it is a difficult test whether human beings can still stand at the top of the biological chain.

(There is already an old book, The Strongest Descends in the City, you can read it.)

- Description from novelbuddy