The Dark King - Chapter 1237: ten million people will be buried with her

Through a mysterious portal, Chen Jin arrived at this strange place – a post-apocalyptic world where civilization had been destroyed.

Consequently, he found –

A piece of metal scrap
A robot trash collector
A battleground
A city
A ton and more of gold
A copy of high-tech documents
A…
In short, Chen Jin found a planet.

- Description from Novelupdates

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

The eldest son of the assassin aristocrat Tuatha Dé.

The skill, experience, knowledge of the previous life, magic, all of which grows his power as an assassin.

Excellent assassins pass through. He was usually admired as the ideal lord, and behind it wielded a blade as an assassin aristocrat.