One Piece: The Rocks Dynasty

No System + ensemble cast + slow burn + nearly invincible + faction building

Rocks D. Kaos, the son of that Rocks, initially wanted only to escape his fate through his own efforts. But the tide of history was against him, and he failed. He could only accept the legacy left by the previous generation.

He possesses an extraordinary, heaven-defying talent. The aura he was born with naturally gives him an advantage over Devil Fruit Users.

Devil Fruits choose their own owners. A fruit that came to him at birth gave him power that could be called invincible.

Relying on his astonishing charisma and knowledge of what was to come, he recruits heroes and champions from every corner of the world.

Through unceasing struggle, he builds the vast Rocks Dynasty and takes part in dividing up the new World Government.

You could also call this the story of me and the next generation striving together.

(The author has heavily reworked the Pirate King world, redistributed its power levels and factions, and added a large amount of original content and characters. Some settings have also been altered, but it's guaranteed to be satisfying.)