The Great Voyage: I Became Nami's Brother at the Start

I never imagined that I'd start out as Nami's brother! And, to make matters worse, the awesome system even gave me a unique Devil Fruit! Now that I have the power, I have to take revenge—that's basic stuff! But who would have thought that after taking my revenge, I'd become a king? Can you believe it? Come on! Let's make this world even crazier!