One Piece: My Skills Think I'm a Good-for-Nothing, Yet They Level Up on Their Own

[No holding back on power scaling] + [No harem for the protagonist] + [Skills become humanized] + [Invincible] + [Multiple female leads]

Roan transmigrates to the world of One Piece and becomes a contemporary of Rob Lucci. His talent is mediocre, and he’s only learned the basics of the Six Powers.

But his first field assessment is tomorrow, and the death rate is 90%!

Then, out of nowhere, his skills come to life!

[“Finger Pistol” thinks it can punch through the heavens and refuses to remain an everyday technique!]

[To prove itself, it runs away from home and starts stabbing like crazy! Stab! Stab! Stab!]

[Congratulations! Your “Finger Pistol” has developed on its own and mastered the “Secret Art: Shockwave”!]

[Congratulations! Your “Finger Pistol” has developed on its own and mastered the “Secret Art: Laser Cannon”!]

[…]

[Congratulations! Your “Finger Pistol” has grasped the true essence of the gun and evolved into the Light of Heavenly Tribulation!]

And that’s not all. As Roan learns more skills, each one starts acting stranger than the last...

While everyone else is sweating through their training, Roan is lounging in a chair, savoring fine wine, and his skills are already on a rampage!