Busoshoku: Koka, One Piece Cruise Wiki

Busoshoku: Koka is a specific form of Busoshoku Haki. This technique somehow uses Busoshoku Haki to harden the body (or parts of it) and weapon which the user is holding. It was first seen used by Monkey D. Luffy, in combination with Gear Third, in order to use his Gomu Gomu no Elephant Gun against the Kraken. The arm became black and shiny and notably did not cause the usual side effect for Gear Third on release. Vergo, Smoker and Zephyr are able to either use this technique or do something sim

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Busoshoku: Koka, One Piece Cruise Wiki

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