Rankyaku is one of the six techniques of "Rokushiki".
The Rankyaku is a powerful projectile technique, in which the users start by kicking at very high speeds and strength, sending out a sharp compressed air blade that can slice objects and greatly damage a human body. However, it has been shown that almost any length of appendage (such as a tail or neck) at high velocities are also capable of this move.
Out of the CP9 agents, Kaku has the greatest mastery of this technique, which he utilizes alongside two blades in his Yontoryu. In addition, despite having no formal training or even general knowledge, he was able to create several new variants of Rankyaku while in his half-giraffe form.
- Rankyaku "Hyobi" - Used by Lucci in his half-leopard form. Rob Lucci creates a large, powerful Rankyaku in the shape of a swirl, which is launched at the enemy like a razor blade. When it hits the opponent, he/she is damaged and stunned, with an ability to send him/her flying if they get caught in mid-air by it.
- Rankyaku "Gaicho" - Used by Lucci. Lucci creates a large Rankyaku in the shape of a bird, but instead of using his legs, he uses his claws in his half-leopard form. This Rankyaku has a much wider range, greater attack power, and is capable of cleaving steel - something not witnessed from other variations. The cut also seems more focused, instead of flickering and jagged like a normal Rankyaku.
- Rankyaku "Sen" - Used by Kaku and Nero in a stomping action. The air is blasted straight ahead in a line towards the opponent like a bullet, instead of in a curve as witnessed in the normal version.
- Rankyaku "Hakurai" - Used by Kaku. A much more powerful form of Rankyaku that is used by using both legs, it appears to cut the air in a larger area. It was shown to be equivalent in strength to Zoro's Nanajūni Pound Hō.
- Rankyaku "Ran" - Used by Kaku. After using Geppo to launch himself into the air, Kaku stabs his swords into the ceiling to stay in the air, then launches multiple Rankyaku with both legs. Each cut is smaller than a normal Rankyaku.
- Rankyaku "Amane Dachi" - Used by Kaku in his half-giraffe form. In this attack, he spins around quickly in a circle while standing on one hand, using his elongated neck to gain extra momentum and spin faster, and then performs Rankyaku with both legs to create a circle shaped Rankyaku which radiates outward. The attack was powerful enough to cut through the outer walls of the Tower of Justice in all directions. It can also be used to send an enormous mass of Rankyaku at the user's opponent, to inflict massive damage. Kaku says that this is his most powerful Rankyaku.
- Rankyaku "Kiri Shigure" - Used by Kaku in his half-giraffe form. After turning himself into a cube with Tekkai "Mushikaku", Kaku uses Rankyaku towards the ceiling with all four of his limbs. There, the vast mass of small Rankyaku blades bounce back, falling like rain on the enemy, making the attack difficult to block, to inflict continuous damage.
- Rankyaku "Neji Hakujin" - Used by Kaku in his half-giraffe form. He does a normal Rankyaku after using his Kyoku Bigan Kirimanjaro, then twists his neck into a screw so the Rankyaku spins in a drill motion.
- Rankyaku "Rodan" - Used by Kaku in his half-giraffe form. Kaku uses an upward Rankyaku with both of his back legs, creating a large cut similar in appearance to a dragon's fang.
- Rankyaku "Shuriken" - Used by Kaku. Kaku fires multiple Rankyaku blades in the shape of shuriken.
- Rankyaku "Koro" - Used by Jabra in his half-wolf form. In this attack, the Rankyaku-cut skips across the ground, bouncing in curves towards the opponent.
- Rankyaku "Lupus Fall" - Used by Jabra in his half-wolf form. In this powerful attack, Jabra shoots four Rankyaku projectiles, each in the shape of a wolf, straight at the opponent. Because of their unusual shapes, these Rankyaku seem to explode upon contact rather than cutting, much like compressed air bullets rather than air blades. Jabra has honed this technique so he is able to initiate it correspondingly with Geppo.
- Rankyaku "Renge" - Used by Kumadori. In this attack, Rankyaku is performed with both legs instead of one, causing multiple cuts on either side of the opponent. The cuts at first appear small and then "blossom" into larger ones, perhaps explaining the name.
- Shiki has shown a technique similar to Rankyaku Ran and Renge, due to having Oto and Kogarashi grafted in his legs, kicking rapidly while floating in midair.
- Donquixote Doflamingo performed a kick of such strength it resembles Rankyaku Amane Dachi, slicing through all three of the Dressrosa palace's towers, without the preparatory spinning.
- In One Piece: Pirate Warriors 3, Koby is also able to perform the Rankyaku as one of his attacks. In Episode of Luffy, Koby is also shown performing an attack similar to Rankyaku but instead of legs, he used it with his arms.