One Piece: New Order - Chapter 83: The New Marine Hero

Born into a world of chaos and violence, young shapeshifter Rhishisikk struggles to survive. With the assistance of unlikely allies, he must learn to live among the most dangerous of monsters – human beings!

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

Lieutenant Jack Fritz is a self centered American man of German descent. He like many joined the United States Navy in hopes of getting an easy life and easy money. In fact getting money and taking it easy is all he has ever really wished for in life.However life seems to have other plans in-store for Jack as he suddenly finds himself at the beginning of World War 3. Though his fight does not last for long as he is suddenly blown to bits by a missile and sent into the afterlife, but instead of going to heaven Jack is dragged to another place where he is given another chance at life by some fiery demon for a price.Having been given no other chance Jack does as the demon says and earns himself life again. Though he doesn't return to his original world, but a medieval one. With no guidance and no higher purpose given to him he simply decides to do the best that he can within this new world of his. This time he will for sure earn that perfect life of his and possibly a lot more.But little does Jack know his fate is not his own and there are many sinister things in-store for him. Also the world he finds himself in is not a safe or simple medieval world, but one beset by dangers from all sides that are already little by little driving humanity towards its extinction.