Naruto System in One Piece - Chapter 260

Yo, Hi! I’m Frank, I made a deal with a demon to pay me some money for receiving a guest for a few days every week.
I had no idea about what I have done.
On May 1st, Conan ‘the God of Death’ came to my house. I was forced to let him in and we get involved in a criminal case.
On May 8th, Bruce Wayne ‘Batman’ came to me. I was forced to follow him to fight crime.
On May 16th, Hannibal Lecter, The Silence of the Lambs, came to my home. I can only say that I really can’t stand my guests.

- Description from Novelupdates

Bai Chuan has a particularly powerful ability, he can take apart everything in the world as a model and choose the best ability structure to give to himself.

If he was born in a mythical world, given him a period of time, he would be able to overthrow the heavens and the world, become an immortal and become an ancestor.

If he was born in a world with extraordinary monsters and beasts, given him a period of time, he could also become the strongest beast, called invincible and immortal.

It’s a pity…he was born in an ordinary world of low martial arts.

“The water in this world is too shallow to raise real dragons…” He looked at the sky and muttered to himself.

Since real dragons cannot be raised in shallow water, wouldn’t it be better to make the pond deeper?

- Description from novelbuddy

One day, Su Mu transmigrated to an alternate world.This world had martial arts practitioners, Qi cultivators and also various types of terrifying ghosts, monsters and demons.In such a hostile environment, his otherwise-perfectly fine reincarnation system became a death system. For him, death was not the end, but rather, a new beginning. From the system, he experienced the profane lives of tens of thousands of demons! In one simulation, he was cut up, thrown into a pot, and eaten. Then, he became a Bloody Skeleton. In another simulation, he was forcefully conscripted and died in battle. His corpse did not decay, and he became a Drought Zombie. In yet another simulation, he was struck by lightning, and his extreme Yin Qi was converted into Yang Qi. He became a Fierce Thunder Ghost. In one more simulation, he consumed spirits, and his murderous aura filled the skies. He became an Undying Ghost Chariot. Some people cultivated to become deities. One other person died a hundred times to become a demon!

The most dependable (sarcastic) assassin -- Gao Xuan.Developing himself with an inventory of powerful gear. A master of biding his time, backstabbing, and brutalizing weaklings.Don’t love me. Nothing would come out of this.I am an assassin without feelings.