When Luffy faced Charlotte Katakuri, raw power wasn't enough. He needed speed, and he needed unpredictability. Enter .
Now, with the advent of (the awakening of his Devil Fruit), Gear Fourth still holds a special place in our hearts. While Gear Five is the peak of "cartoonish freedom," Gear Fourth is the peak of "rubbery science." It is the bridge between Luffy as a scrappy underdog and Luffy as a Yonko contender.
By using Haki to maintain his body's shape despite the internal air pressure, he turns his rubber body into a highly compressed, spring-like weapon. gear fourth one piece
Furthermore, Gear Fourth serves as the ultimate rebuttal to the series’ recurring villains. Doflamingo’s “Parasite” strings control people, robbing them of free will. Kaido’s brute force crushes spirits into submission. Against such world-breaking power, simple speed or strength is insufficient. Luffy needs a technique that embodies overwhelming, crushing liberation . The “King Kong Gun”—a fist the size of a house, compressed and released—is not a punch; it is a declaration that no chain, string, or scale can bind a truly free will. By sacrificing his sleek silhouette for a hulking, tyrannical form, Luffy symbolically becomes the monster necessary to slay other monsters. He does not enjoy this form; he endures it. The strained veins, the constant Haki drain, and the eventual collapse all suggest that Luffy hates this side of himself. But he uses it because the freedom of his friends is worth the temporary loss of his own.
Luffy inflates his muscular structure rather than his bones or blood vessels. But the key ingredient is . By coating his inflated muscles in Haki, he creates a structure that is paradoxically bouncy yet incredibly durable. He describes it as a "Rubber Man" becoming a "Rubber Balloon," but one that hits like a cannonball. When Luffy faced Charlotte Katakuri, raw power wasn't enough
Boundman’s fighting style is unpredictable. He bounces off the floor, walls, and air, making him difficult to target. It is a form designed for all-out assault, overwhelming enemies with raw power and speed simultaneously.
While Boundman was born from Luffy’s training to destroy, was born from necessity—and hunger. Now, with the advent of (the awakening of
In the sprawling narrative of One Piece , power is rarely depicted as a simple virtue. For Monkey D. Luffy, the protagonist, every significant escalation in strength—from Gear Second to Gear Third—has come at a physiological cost: reduced lifespan, swollen limbs, and temporary helplessness. However, no transformation embodies the series’ central thematic conflict between freedom and burden quite like . Introduced during the desperate climax of the Dressrosa arc, Gear Fourth is not merely a physical evolution; it is a visual and philosophical manifesto. It represents the moment Luffy must surrender his iconic, carefree elasticity to become a tyrant of brute force, revealing that to protect the freedom of others, he must temporarily imprison himself in a monstrous cage of muscle.
: Its appearance is inspired by Niō statues , the wrathful guardian deities found at Japanese temple entrances.