Monkey D. Luffy first reveals in Episode 726 of the One Piece anime, titled "Gear 4! The Phenomenal Boundman!" . In the manga, this iconic transformation debuts in Chapter 784 .

: Introduced during the Whole Cake Island Arc in Episode 806 (Chapter 842) . Luffy used this form to defeat Charlotte Cracker by utilizing his massive size after eating a mountain of biscuits to reflect attacks.

Luffy unlocks Gear Fourth in the climax of the Dressrosa Arc , specifically during the final battle against Donquixote Doflamingo.

This power-up occurs during the climax of the during Luffy's high-stakes battle against Donquixote Doflamingo . After his Gear 2 and Gear 3 attacks fail to break through Doflamingo's defenses, Luffy is forced to unleash the technique he developed during his two-year training on Rusukaina. The Three Forms of Gear 4

Gear 4, also known as "Boundman," significantly enhances Luffy's physical abilities, granting him increased strength, speed, and durability. This transformation allows Luffy to inflate his body like a balloon, making him more resistant to attacks and enabling him to deliver devastating blows.

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