MTL - I, The New Hokage of Konoha - Chapter 43 research experiment

Crossing into the world of Naruto, and acquiring the One Piece system, with all the powers of the world of One Piece, swordsmanship, devil fruit, domineering.

-Do you think that your fire is very powerful? I have the burning fruit.

-Do you think that your thunder is very powerful? I have a thundering fruit.

-Do you think that your otter is very powerful? I have the frozen fruit.

-Did you said you want to die? Don’t worry, I also have a nickname: Death Doctor.

- Description from Novelupdates

Jung Sunwoo was an average man. He had just taken his first job at W&U, a celebrity management company, as a manager. He could finally achieve his dream of being the manager of a world-famous actor or actress. On his way to work, he fell into what appeared to be a lucid dream about his future. As he went on with his day, he realized it may not have simply been a lucid dream.

The World of Ephesus. A vast world plagued by Breaches containing countless Beasts of Corruption. A World on the brink of ruin as the Four Human Lineages defend the last bastions of Humanity! With the power of Gem Masters standing against the Beasts of Corruption, the flames of Humanity seek to burn ever brighter. In such a world, in the Mortal Branch of the Asmodeus Bloodline, Alexander awakens a Gem Socket that others consider defective. A Variant Gem Socket. Looked down upon by those who do not understand it, this supposed defect may just be the solution that the burning embers of humanity were waiting for. Follow Alexander as he entirely warps the perception of what a Gem Master is- as he embarks on a journey to become...The Empyreal Gem Master!

A biker tries to save a cat on the highway and gets hit by a truck (Truck-Kun), he was rushed to the hospital but, due to internal bleeding, he dies only to be reborn as a cat, in a new world with a system.

In this new and vast world, he tries his best to get used to his new body and get stronger along the way. With his overpowered system and skills. To one day become untouchable.