One Piece Luffy has five gears. First, everything is unified. From the course of Luffy, we can find that Luffy was a normal person at first, and then he began to develop into a third-gear giant. Later, Luffy compressed the giant with the third gear, and with the fourth gear, the last form of the fourth gear, the snake man, was basically close to the size of a normal person.

The origin of a piece

Nine hundred years ago, twenty kingdoms united to form an organization. Eight hundred years ago, this organization became the present world government, and the original twenty royal families became the descendants of God-Celestial Dragons. What happened in the past 100 years was erased by the world government, and no one knows.

What we know now is that there was once a very prosperous ancient kingdom, but somehow it disappeared. Roger, the former One Piece, dominated the second half of grand line, knowing the historical truth, but voluntarily surrendered to the navy, and opened the era of One Piece with his last words.