When Luffy fought Kaido, he utilized Snakeman with Advanced Conqueror’s Haki, proving that Gear 4 was not just a temporary gimmick, but a viable combat style for an Emperor of the Sea.
Gomu Gomu no King Kong Gun , Leo Bazooka , Culverin . 2. Tank-Man (Stuffed Version) one piece gear 4
Visually, Gear Fourth is a shock. By biting into his arm and inflating his muscles rather than his bones (as in Gear Third), Luffy transforms into : a bouncing, oversized titan with haki-coated arms and steam trailing behind him like a rocket’s exhaust. Oda draws heavily from the aesthetics of rubber hose animation —the bouncy, limb-stretching cartoons of the 1920s. When Luffy fought Kaido, he utilized Snakeman with
The original and most recognizable form. Luffy takes on a bulbous appearance, his skin glows red from the tension, and steam emits from his body. In this state, Luffy constantly bounces; he cannot stand still. This perpetual motion allows him to utilize the "Python" technique—changing the direction of his attacks mid-air by tensing and relaxing his muscles, making his punches impossible to predict. Tank-Man (Stuffed Version) Visually, Gear Fourth is a
[ Gear 4 Activation ] │ ├──► 1. Muscle Inflation (Kintoki) via biting into the forearm. │ └──► 2. Armament Haki (Busoshoku) compression across the skin. │ └──► Result: High-tension rubber with immense kinetic recoil.
Compare the of Gear 4 directly with the newly debuted Gear 5 .
This compression turns Luffy's body into a spring. He is no longer just a rubber man; he is a high-tension projectile. The Haki prevents his body from stretching loosely; instead, he snaps back with immense velocity and force, allowing him to pierce the defenses of Haki users like Doflamingo and Kaido.