Doflamingo famously notes that Luffy remains "rubbery" even while hardened by Haki—a feat previously thought impossible.
: He coats large portions of his body in Armament Haki , which allows him to maintain a rubbery flexibility even while hardened. when is gear 4 introduced
Gear 4 is introduced during the Dressrosa Arc , specifically during the climax of the battle between Monkey D. Luffy and Donquixote Doflamingo . After realizing that his previous attacks and Gear 2nd and 3rd are insufficient to defeat the Shichibukai, Luffy reveals this new form to turn the tide of the battle. Doflamingo famously notes that Luffy remains "rubbery" even
This is the first time we see moves like the Gum-Gum Kong Gun and Leo Bazooka , which possess enough force to send Doflamingo flying across the entire island. The Trade-off Luffy and Donquixote Doflamingo
Gear 4 makes its debut in Chapter 784 of the One Piece manga, titled "Gear 4."