This article contains spoilers from One Piece's Elbaf Arc. Luffy's mastery over Gear 4 allows him to use it in specific body ...

After learning Haki, Luffy managed to combine it with his Devil Fruit powers, and ended up creating Gear 4, which works on the concept of inflating muscles, as Luffy calls it muscle balloon.

One Piece's latest chapter reveals a new threat on Elbaf, setting up a perfect battle for Luffy's imaginative Gear Five powers.