The world of One Piece has two primary power systems that Eiichiro Oda expanded upon at different parts of the story. In One Piece Chapter 1, released on July 18, 1997, in Shueisha's Weekly Shonen Jump Issue 34, Eiichiro Oda introduced Devil Fruit to us for the very first time, which forms the primary power system of the world. In One Piece Chapter 597, which was officially released on August 30, 2010, in Shueisha's Weekly Shonen Jump Issue 39, Oda expanded upon Haki for the very first time and fully explained to fans what this new power system was going to be.
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