The significance of this moment extends beyond mere aesthetics. Unlike the speed of Gear Second or the blunt force of Gear Third, Gear Fourth utilizes elasticity in a revolutionary way: compression. By contracting his inflated muscles, Luffy creates immense tension, allowing him to bounce across the battlefield at incredible speeds and deliver strikes like the “Kong Gun”—a punch so powerful that it warps the air and sends Doflamingo flying through several city blocks. Episode 726 captures this moment of awe and terror, as even the unflappable Doflamingo is shown bleeding from the mouth, realizing that the "Straw Hat" has entered a realm he cannot easily follow.

In conclusion, is the definitive answer to when Luffy uses Gear Fourth for the first time. It is not merely an episode containing a fight; it is a turning point in the One Piece power scaling. It showcases Luffy’s ingenuity in weaponizing his own biology, the profound mastery of Haki required to sustain the form, and the desperate courage needed to risk total exhaustion. For fans, the image of Boundman bouncing defiantly in front of Doflamingo remains an iconic testament to the lengths Luffy will go to protect his crew and liberate an island.

The episode itself is a masterclass in anime escalation. After being launched into the atmosphere, Luffy bites into his own arm—a callback to how he inflates his bones for Gear Third. However, this time, he does not blow air into his bones but rather into his . The result is visually shocking: Luffy’s arm swells to colossal proportions, followed by his entire torso and legs, transforming him into a hulking, bouncing titan covered in dark, swirling patterns of Busoshoku Haki (Armament Haki). The technique is named Gear Fourth: Boundman .

To understand the gravity of Episode 726, one must consider the context. Doflamingo, a Warlord of the Sea with a terrifying mastery of the Ito Ito no Mi (String-String Fruit), had pushed Luffy to his absolute limit. Their battle atop the royal plateau saw Luffy’s previous Gears fail repeatedly; Doflamingo’s “Awakened” string powers could slice through an entire city and repair his own internal organs. After a temporary ceasefire involving the gladiators and Trafalgar Law, Luffy realized that standard tactics would lead to defeat. Thus, he sought a technique he had been developing specifically to counter massive, durable opponents: Gear Fourth.

In the sprawling narrative of Eiichiro Oda’s One Piece , few moments carry as much raw intensity and narrative weight as the debut of a new Gear. Following the immense physical toll of Gear Second and the grotesque inflation of Gear Third, Monkey D. Luffy’s next evolution was not just a power-up—it was a desperate necessity. The first episode in which Luffy unleashes Gear Fourth is Episode 726 (titled “Gear Fourth! The Bouncy Man of Fury”). This transformation occurs during the climactic battle against the formidable Donquixote Doflamingo on the island of Dressrosa.

Furthermore, Episode 726 establishes the critical weakness of Gear Fourth: the Haki drain. After using the form, Luffy is rendered completely immobile and unable to use Haki for ten minutes, shrinking into a tiny, exhausted figure. This risk-reward dynamic elevates the tension, proving that even this god-like power comes at a terrible price.