|King Kong Gun|
Luffy using King Kong Gun.
|Effect||Luffy enters Gear Fourth to deliver a powerful, long-ranged punch.|
When performed, Luffy first uses Kenbunshoku Haki to create a black line of sight in front of him, paralyzing and dealing 10% damage to opponents hit. He then coats and inflates his arm to enter Gear Fourth before compressing his fist into his forearm. After reeling it back, he then delivers a powerful punch, which stretches out to cover a massive horizontal range. Opponents hit by the punch are dealt 31% damage with extreme knockback, which often is enough to one-hit KO. After the punch ends, Luffy returns to his normal form, ending the move.
Gum-Gum King Kong Gun is a powerful technique Monkey D. Luffy uses in One Piece. It can be performed using the Gear Fourth, a technique in which Luffy coats his arm in Busoshoku Haki and blows so much air into his body that he becomes massively inflated, particularly in his muscles. While using Gear Fourth, Luffy's strength, speed, and durability are greatly increased, but he can only use the form for so long before it automatically deactivates and leaves Luffy exhausted. Gum-Gum King Kong Gun is a technique Luffy uses in his first Fourth Gear form, Boundman, in which he compresses his fist into his enlarged forearm, blows more air into it to increase its size, and then unleashes a massively powerful punch. It is one of the most powerful techniques Luffy has ever utilized in any form.
The kanji text that hovers over him if the attack connects reads "ドオン！！", a common sound effect that is found in the One Piece manga and in fighting games such as One Piece: Super Grand Battle! X and One Piece: Burning Blood.
|Luffy's special moves|
|Standard special move||Gum-Gum Pistol|
|Side special move||Gum-Gum Rocket|
|Up special move||Gum-Gum Snap|
|Down special move||Gum-Gum Balloon|
|Final Smash||King Kong Gun|