Nico Robin haki + rokushiki by xMrNothingx on DeviantArt

Geppo, One Piece Wiki

One Piece Gold - Rob Lucci's vivre card said that: The training required for the acquisition of rokushiki is akin to that used for acquiring haki. Akin = in the family Rokushiki

Rokushiki, Wiki

Rokuogan, One Piece Wiki

What if Rokushiki is Haki based?

What power is it? : r/OnePiece

Vivre Card Databook – Index Set (some new information) – The Library of Ohara

One Piece: Strongest Abilities That Are Not Devil Fruit Or Haki

Chapter Discussion - Rokushiki is based on Haki, Page 3

Konoha: Deduce Rokushiki and Armament Haki at the Start! Latest Chapter - MTLNATION