One Piece: I'm the Strongest Mercenary

Half-invincible + Ruthless and Decisive + Devil Fruit Powers + No Allegiance + Cunning (The System appears, but not much.)

Top-tier physical combat, swordsmanship, and Haki. There's a development phase early on.

He transmigrates into the world of pirates and awakens the Strongest Mercenary System.

Facing Shanks: “Your reputation? What reputation? You're nothing! I'm killing that deserter king, and nobody can stop me, not even the King of Heaven!”

Magellan: “The money has already been sent. I'll leave the Impel Down riot to you!”

Doflamingo: “Fufufu! (Bawling) Everything I did was to earn your approval, big brother!”

Akainu: “Cro will join the Marines today, no matter what. He thinks the position is too low? Then we'll go from Three Admirals to Four!”

In this chaotic Great Pirate Era, who can put an end to him once and for all? The Marines? Forget it. Only I, Torlet Cro, can put an end to everything!