Valkyrie's Shadow - Chapter 4Birthright: Act 2,

He—an enigmatic and cold-blooded soldier with a mysterious background.
She—a ruthless and bloodthirsty spy.

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

Transmigrating to the disciples of the Demon Sect, and relying on the skill modifier to become a giant of the Demon Dao.

[Detected the technique “Blood Nerve”, relying on devouring blood to practice]

[Side effects: easily affected by the spirit contained in the blood, becoming bloodthirsty, bloodthirsty, mad, and even brain dead]

[Please wait a moment, the system is being modified…]

[Ding! The modification is complete, and the side effects are cancelled]

- Description from novelbuddy

Monsters, both human and beast, surrounded him. He needed power to survive this new world... but he arrived as a mortal.One moment William was at work. The next, he was captured by lunatics.He had never believed in the fantastical, but he had no choice after finding himself in another world surrounded by demonic cultivators trying to extract his soul. If he couldn't find an escape, his journey would end just as abruptly as it started.William was inches from death when a benevolent cultivator saved him from that fate. Seeing his pitiful state, the cultivator decided to give him an opportunity in the form of a tool: A system to guide him on the path of cultivation.William would use it to claw his way to the peak of the cultivation world.