Rokushiki

Rokushiki (六式) is a special, superhuman martial arts style. In the Viz Manga, they are called the Six Powers. They each made their appearances in different Chapters and Episodes, but the technique made its debut when one of the moves appeared in Chapter 342 and Episode 242. It was first introduced being used by the CP9 agents.

The strength of a Rokushiki user is measured by Doriki, which Fukuro can use his "Te-awase" to calculate with. The higher the level, the stronger each technique's potency becomes. Most of the users have their own variation of each technique, to increase their versatility and originality. Also, certain users tend to be more specialized in one technique, such as Kaku with Rankyaku, Jabra with Tekkai, Fukuro with Soru, and Rob Lucci with Shigan.

The Rokushiki style are the main style of combat for the World Government secret CP9 agents, but some Marines have also demonstrated its usage. Coby used Soru against Monkey D. Luffy, and later Vice Admirals Momonga and Dalmatian used it to confront Luffy at Marineford. It is unknown exactly how much the Rokushiki technique is spread around the Marines. Outside weapons and Devil Fruits, the series is very obscure about which technique overall Marine combatants use.

Kami-e
But there's no art to being hit...

The Kami-e (紙絵) makes the users' body go limp in order to avoid any attacks, and float like a piece of paper. In the FUNimation dub, this is called Sketch, and in the Viz Manga, this is called Paper Art.

Variations of Kami-e

 * Seimei Kikan: Kami-e Bushin (生命帰還　紙絵武身): Used by Rob Lucci. Using Seimei Kikan (Life Return, the same Sennin technique as Kumadori), he makes his half-leopard form smaller, lighter, and possibly increasing his speed. At any rate, he is much more agile in this form, and harder to hit - as opposed to his hulking normal half-leopard form. In the FUNimation dub, this is called Rebirth: Sketch Form, and in the Viz Manga, this is called Life Return Paper Art Fighting Form.


 * Seimei Kikan: Kaijo (生命帰還　解除): Used by Rob Lucci while in his smaller half-leopard form. It cancels his Seimei Kikan: Kami-e Bushin technique, and returns to his larger, stronger half-leopard form. In the Viz Manga, this is called Life Return Release.


 * Kami-e "Slime" (紙絵「軟泥」): Used by Fukuro. Instead of the body becoming limp like paper, it stretches and moves in ways slime or sludge would move in order to avoid attacks. In the Viz Manga, this is called Paper Slime.

Geppo
One can also kick the air to float...

The Geppo (月歩) allows the users to actually jump off the air itself, allowing them to stay in the air for much longer than usual. CP9 members can use this technique to cross great distances without ever touching the ground, or set themselves up for swift, aerial attacks. No CP9 member has yet shown any variations of the technique, with the exception of Lucci's Kamisori and Fukurou's one legged Geppo (which in theory, other Geppo users may have the capability to do). It has once been used aggressively by Lucci, performing a suplex-styled move while Luffy clung onto his back. The impact left a rather large crater in the floor. While the technique itself affords several advantages in both in and out of battle for the user, it has but one major weakness: since its usage depends heavily on the user's legs, restraining or pinning down any major parts of their lower body can significantly disrupt Geppo. This was seen during Fukurou's fight with Franky, where the latter managed to grab on to one of the CP9's legs, noticeably affecting the technique. However, it should be noted that Rob Lucci has been seen kicking off the air with one leg at a time rather like hopping and keeping himself afloat. In the FUNimation dub, this is called Geppo, and in the Viz manga and FUNimation subs, this is called Moonwalk.

Sanji has developed his own version of this technique called "Sky Walk" on the Kamabakka Kingdom.

Rankyaku
It is possible to be fast enough to cause slicing winds...

The Rankyaku (嵐脚) 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. In the FUNimation dub, this technique keeps its original name, and in the Viz Manga, this is called Tempest Kick.

Variations of Rankyaku

 * Rankyaku "Hyobi" (嵐脚「豹尾」): 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. In the FUNimation dub, this is called Rankyaku: Leopard Tail, and in the Viz Manga, this is called Tempest Kick Leopard Tail.


 * Rankyaku "Gaicho" (嵐脚「凱鳥」): 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. The "Gaichou" can also mean "Injurious Bird". In the FUNimation dub, this is called Rankyaku: Gaicho, and in the Viz Manga, this is called Tempest Kick Victory Bird.


 * Rankyaku "Sen" (嵐脚「線」): 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. In the Viz Manga, this is called Tempest Kick Line when used by Nero and Tempest Kick Straight Line when used by Kaku.


 * Rankyaku "Hakurai" (嵐脚「白雷」): 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. In the Viz Manga, this is called Tempest Kick White Thunder.


 * Rankyaku "Ran" (嵐脚「乱」): Used by Kaku. After using Geppou 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. Lucci also used a version of this attack (without the swords) during his fight with Luffy, but he did not name it. The "Ran" can also mean "War". In the Viz Manga, this is called Tempest Kick Slaughter.


 * Rankyaku "Amane Dachi" (嵐脚「周断」): Used by Kaku in his half-giraffe form. In this attack, he spins around quickly in a circle on one hand while performing Rankyaku 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. In the FUNimation dub, this is called Rankyaku: Amane Dachi, and in the Viz Manga, this is called Tempest Kick Sky Slicer.


 * Rankyaku "Kiri Shigure" (嵐脚「麒麟時雨」): 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. The "Kiri" part of the name can also mean "mist". In the Viz Manga, this is called Tempest Kick Giraffe Shower.


 * Rankyaku "Neji Hakujin" (嵐脚「ネジ白刃」): 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. In the Viz Manga, this is called Tempest Kick Spinning White Blade.


 * Rankyaku "Rodan" (嵐脚「龍断」): 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. In the Viz Manga, this is called Tempest Kick Dragon Cut.


 * Rankyaku "Shuriken" (嵐脚「手裏剣」): Used by Kaku. Kaku fires multiple Rankyaku blades in the shape of shuriken. In the FUNimation dub, this is called Rankyaku: Shuriken, and in the Viz Manga, this is called Tempest Kick Shuriken.


 * Rankyaku "Koro" (嵐脚「孤狼」): Used by Jabra in his half-wolf form. In this attack, the Rankyaku-cut skips across the ground, bouncing in curves towards the opponent. In the Viz Manga, this is called Tempest Kick Lone Wolf.


 * Rankyaku "Lupus Fall" (嵐脚「群狼連星」): 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 Geppou. In the Viz Manga, this is called Tempest Kick Lupus Fall.


 * Rankyaku "Renge" (嵐脚「蓮華」): 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. In the Viz Manga, this is called Tempest Kick Lotus.

Shigan
A bullet isn't needed to pierce the human body.

The Shigan (指銃) is a close-quarter combat technique, in which the user pushes their finger into a certain target at a very high speed, leaving a wound similar to a bullet wound, making guns unnecessary. It is a very useful technique that can connect rapidly and accurately, which works well with the rokushiki users' impressive speed and agile techniques. However it's never been used to counter or deflect another powerful attack in any fights, which is probably because the user could easily break his finger instead of just blocking it with Tekkai. The Shigan's shape is derived from the shape of the finger, hence the hit of Shigan will have more of an impact on Luffy's rubber body (which normally reflects bullets) if it is sharper than the round bullet and resembles more modern bullets.

A sharper point is added to this technique when Lucci, Jabra and Dalmatian morph into their half-beast forms, enabling the use of their claws to fire the Shigan like an actual modern bullet, instead of simply jabbing their opponent. So far, it seems each CP9 member has their own version of Shigan, aside from Blueno, Nero, and Spandam, the latter two not even knowing how to use the technique. In the FUNimation dub, this technique keeps its original name, and in the Viz manga and FUNimation subs, this is called Finger Pistol.

In a fan question on SBS, Oda said that if you got poked in the butt with a Shigan, you'd die. In another SBS, Oda also claimed that the CP9 agents would sprain their fingers when they failed in the technique during training.

Variations of Shigan

 * Shigan "Oren" (指銃「黄蓮」): Used by Lucci. This attack is simply a rapid-fire version of the normal Shigan technique that hits the enemy multiple times. In the anime, he is also seen using this technique to kill the captain of a crew who raided the kingdom 15 years ago, but did not name it as "Oren". In the FUNimation dub, this is called Shigan: Yellow Lotus, and in the Viz Manga, this is called Finger Pistol Yellow Lotus.
 * Tobu Shigan "Bachi" (飛ぶ指銃「撥」): Used by Lucci. A projectile version of Shigan that fires sharp compressed air bullets from the fingers, similar to "Rankyaku", and are therefore able to pierce Luffy's rubber body. Unlike all other versions, this type of Shigan is launched by flicking instead of jabbing. Although in the anime, Lucci and Jabra demonstrated a variant that involves jabbing. In the Viz Manga, this is called Flying Finger Pistol Sting.


 * Tobu Shigan "Mitsubachi" (飛ぶ指銃「三撥」): Used by Lucci. Same as above, except Lucci launches it three times in three rows. This is an anime only technique.


 * Tobu Shigan "Hibachi" (飛ぶ指銃「火撥」): Used by Lucci. Same as Tobu Shigan: Bachi, except that the projectile is a fireball, possibly created through friction, that burns the victim upon impact. This is an anime only technique. "Hibachi" is a type of Japanese grill.


 * Shigan "Madara" (指銃「斑」): Used by Lucci. Appears as Ouren, but is performed with both hands instead of one and in half-leopard form (meaning that his fingers are clawed), this makes for the ultimate Shigan barrage. In the FUNimation dub, this is called Shigan: Spots, and in the Viz Manga, this is called Finger Pistol Spots.


 * Bigan (鼻銃): Used by Kaku, in his half-giraffe form. In this attack, Kaku uses his nose instead of his finger to perform the attack. As his nose is much larger in diameter than a finger, the hole it creates is also much larger than that of a normal Shigan, as well as being completely square. In the FUNimation dub, this is called Shigan: Nose Gun, and in the Viz Manga, this is called Nose Pistol.


 * Kyoku Bigan "Kirimanjaro" (極・鼻銃「麒麟マン射櫓」): Used by Kaku in half-giraffe form. After using Kirin Hodai, he can fire his neck out like a cannon, making his Bigan stronger. The name Kirimanjaro is a reference to "Kilimanjaro", the mountain that shares the same name. In the Viz Manga, this is called Extreme Nose Pistol Giraffe Blast.


 * Jushigan (十指銃): Used by Jabra in his half-wolf form. In this attack, Jyabura puts both of his hands together and performs Shigan with all ten of his clawed fingers at once, greatly damaging the opponent. In the Viz Manga, this is called Ten Finger Pistol.


 * Gekko Jushigan (月光十指銃): A combination of Juushigan and Geppou. After using Geppou to get himself into the air and subsequently avoid his foe's attack, Jabra finally uses it to launch himself towards his airborne target in a vertical drop. The added momentum and the vulnerable target makes the following Juushigan more effective, and harder to avoid. In the Viz Manga, this is called Moonlight Ten Finger Pistol.


 * Shigan Cue (指銃 Q): Used by Kumadori. In this attack, Kumadori uses his blunt staff in the same way a finger is normally used in Shigan. The Q in the name is a reference to a pool cue, which is held in the same manner that Kumadori wields his staff. In the Viz Manga, this is called Finger Pistol Q.


 * Shishi Shigan (獅子指銃): Used by Kumadori. Rather than using his own fingers, Kumadori shapes his hair into the form of hands and repeatedly uses the fingers of said hands to rapidly jab the opponent, similar to Lucci's Shigan "Madara", but less powerful. In the Viz Manga, this is called Shishi Finger Pistol.


 * Jugon (獣厳): Used by Fukuro, this is a very strong punch which is done at the same speed as Shigan, making it even more powerful. In the Viz Manga, this is called Solid Beast.


 * Jugon Ogi: "Fukuro Dataki" (獣厳「奥義」"梟叩き"): A rapid-fire version of Jugon, in which Fukuro unleashes a flurry of punches at the enemy while using Soru to move around him, in order to strike from all directions. In the Viz Manga, this is called Solid Beast Supreme Technique Owl Strike.


 * Shinaru Shigan "Whip" (しなる指銃「鞭」): Used by Kalifa. In this attack, Kalifa pulls back her arm as if to use a normal Shigan attack, then whips her arm out at the opponent at high speed, causing her arm to appear as if it is bending like a whip would, and hits the enemy with her finger. The whip aspect of this variation results in the added effect of the target being thrown forcibly backwards. In the Viz Manga, this is called Bendy Finger Pistol Whip.

Soru
With leg strength explosive enough to seemingly cause one's body to "disappear"...

The Soru (剃) allows the users to move at extremely high speeds in order to avoid attacks, as well as to attack at higher speeds and with greater power. It was revealed that the principle of this move was to kick off the ground at least ten times in the blink of an eye. Luffy has also learned from this move and was able to use it in his fights against Blueno, Rob Lucci, and Mihawk, though Luffy's own version (via Gear Second) is swifter and more powerful.Coby was seen being able to use this move during his friendly fight with Luffy after the Enies Lobby arc. As Nero lacked the complete training, his Soru is actually more of a swift run instead of the vanishing speed seen from other Soru users. In the Viz Manga and FUNimation subs, this is called Shave.

Another thing that should be noted of this particular skill is that Kuro's "Shakushi" travels at roughly the same speed as CP9's Soru ability. The difference is that when Kuro uses that technique, he cannot see what he is attacking, or how far he is going, whereas CP9 have mastered this ability and therefore can. The fact that other people, outside of CP9 membership has exhibited being able to imitate the skill (either by copying the move directly or developed their own version of it) suggests that Soru might be the most fundamental of Rokushiki. This is supported by the fact that Coby uses (and masters) Soru, though he has not shown the ability to use any other Rokushiki techniques.

Variations of Soru

 * Kamisori (剃刀): Used by Lucci. A combination of Geppo and Soru, where Lucci uses Soru in a zigzag motion in midair, allowing extremely fast movements in three dimensions. In the Viz Manga, this is called Razor.


 * Soru "Tekkai Dama" (剃「鉄塊玉」): Used by Fukuro. In this attack, Fukuro spins his body at great speeds towards his opponent using Soru, then uses Tekkai to harden his spherical body. In the Viz Manga, this is called Shave Iron Ball.


 * Cho Sokuten Tekkai Dama (超側転　鉄塊玉): A variation on the above technique used by Fukuro wherein he combines his usual Tekkai Dama movements with Geppo to use it in midair. In the Viz Manga, this is called Super Cartwheel Iron Ball.


 * Gear Second: Used by Monkey D. Luffy. He performs this by pumping his rubber legs instead of hitting them against the ground for impulse. The resulting usage of Soru is more efficient and possibly faster than the standard version. He maintains this speed until the Gear's duration time finishes. His strength increases as well as his speed. He uses this in conjunction with his rubber body and superhuman strength to perform high speed versions of his standard attacks, that have much more power and are invisible to the average eyesight of a human. First used in the 7th movie by accident, but was officially introduced in Luffy's fight against Blueno. In the Viz Manga, this is called Gear Two.

Tekkai
We've trained our bodies such that we can turn them into "Iron Carapaces" if we so choose...

The Tekkai (鉄塊) hardens the users' muscles to the level of iron, in order to nullify damage taken from attacks. However, it can be broken by strong enough forces such as Luffy's various Gears, Roronoa Zoro's Shishi Sonson and Tatsumaki, Sanji's Diable Jambe and Franky's Strong Hammer. When Tekkai is active, the user is unable to move, with the exception of Jabra's Tekkai Kenpo. Tekkai can also be used to enhance the users attacks, Similar to Busoshoku Haki. The strength of Tekkai can vary for users with different physical conditions, as a person with a higher level of muscular strength would be able to take stronger forces with his/her use of Tekkai. Furthermore, despite the increased physical density that one gains when activating this move, one should remember that the user's body is still flesh and blood. Thus, its resistance to other than solid attacks remain pretty much the same, making the user as vulnerable as ever to certain attacks. An example was during Sanji's fight with Jabra where he used the burning force of friction to incinerate through the latter's Tekkai or when Franky used his actual iron fist to break through Fukuro's Tekkai. As such, even masters of Tekkai are far from indestructible. However, for Rob Lucci, he seemed to be able to resist even cannonball flames at 13 years old. In the Viz Manga and FUNimation subs, this is called Iron Body.

Variations of Tekkai

 * Tekkai "Utsugi" (鉄塊「空木」): Used by Lucci. This form of Tekkai is used entirely as a counter instead, where the purpose isn't to absorb damage from the attack, but to transfer the shock of the attack back to the attacker, which can lead to broken bones in a normal human body. In the Viz Manga, this is called Iron Body Empty Tree.


 * Tekkai "Mushikaku" (鉄塊「無死角」): Used by Kaku in his half-giraffe form. Kaku bends his neck and legs to shift himself into a cube. When Tekkai is used in this form, he eliminates the weak points of his body, particularly his neck, and ensures that not a single spot is vulnerable to his following Kiri Shigure, though he looks ridiculous to his opponents. The pun is that "mashikaku", means "perfect square". In the Viz Manga, this is called Iron Body Edgewise.


 * Tekkai Kenpo (鉄塊拳法): Used by Jabra. Using Tekkai Kenpo, Jabra is able to move while using Tekkai. Tekkai Kenpō is also an entire fighting style, with various techniques of its own. In the Viz Manga, this is called Iron Body Kung Fu.


 * Tekkai Kenpo "Okami Hajiki" (鉄塊拳法「狼弾」): After hardening his hands with Tekkai, Jabra punches his opponent. In the Viz Manga, this is called Iron Body Kung Fu Wolf Bullet.


 * Tekkai Kenpo "Roga no Kamae" (鉄塊拳法「狼牙の構え」): Simply called Rōga for short. Rōga is one of Jabra's forms of Tekkai Kenpō. The way that Rōga is called is a pun in Japanese; oftentimes sentences end with darou, approximately meaning "probably". Sometimes, however, the particle ga would be added onto the end of a sentence to make it seem more direct. This is the way Jabra normally speaks, so he simply replaces where he would normally say darou ga (だろうが) with da rouga (だ狼牙). In the Viz Manga, this is called Iron Body Kung Fu Wolf Fang Stance.


 * Tekkai Kenpo "Roba no Kamae" (鉄塊拳法「狼芭の構え」): A form of Tekkai Kenpō, in which Jabra seems to combine Tekkai with Soru in order to move at extreme speeds. In the Viz Manga, this is called Iron Body Kung Fu Wolf Fang Stance.


 * Rokaru Area Network (狼狩エリア・ネットワーク): While moving at high speed, Jabra slashes at his opponent with both hands. Because of his high speed, it appears as if he was attacking with multiple hands. "Roukaru" is the Japanese way of pronouncing the word "local", making this attack a pun on "local area network". In the Viz Manga, this is called Wolf Hunt Highspeed Scratch.


 * Tekkai Kenpo "Don Poro" (鉄塊拳法「重歩狼」): A punch to the opponent's stomach with Tekkai in use. "Dongpo Rou" can also mean simmered square pork meat in Chinese. In the Viz Manga, this is called Iron Body Kung Fu Don Po Ro.


 * Tekkai Kenpo "Matenro" (鉄塊拳法「摩天狼」): Jabra flips onto his hands, then kicks his opponent up into the air. In the anime, this attack was portrayed as a jumping kick instead. "Matenro" is also Japanese for "skyscraper". In the Viz Manga, this is called Iron Body Kung Fu Devil Wolf.


 * Tekkai "Rin" (鉄塊「輪」): Used by Blueno. Blueno uses Tekkai and kicks one leg into the ground and starts rotating his legs at a fast speed, causing his legs to simultaneously slam into the ground on a set path toward his opponent. It also seems to incorporate Rankyaku, as the legs leave blue traces in the air like a normal Rankyaku shockwave and a glancing attack cut a small amount of Luffy's hair. In the Viz Manga, this is called Iron Body Wheel.


 * Tekkai "Sai" (鉄塊「砕」): Used by Blueno and Kibin. After using Geppou to project himself towards his opponent, Blueno uses Tekkai to harden his body, smashing the enemy. In the Viz Manga, this is called Iron Body Smash.


 * Tekkai "Go" (鉄塊「剛」): Used by Blueno and Kumadori. Visually, the move differs from the ordinary Tekkai in that the user visually tenses his body even further while standing still; the ordinary Tekkai could be activated seamlessly. According to Blueno, it is his strongest form of Tekkai. In the Viz Manga, this is called Iron Body Strength when used by Blueno, and Solid Iron Body when used by Kumadori.

Rokuogan
Let me show you... the most powerful attack available to those with full mastery of Rokushiki.

The Rokuogan (六王銃) is the secret and ultimate attack of the Rokushiki style. Rob Lucci states that only those who have absolute mastery of the other six skills can have access to this seventh skill. The user places both his/her fists right in front of the target and launches a devastating shock wave, which seems to have the same power as an Impact Dial or even a Reject Dial (depending on the amount of energy absorbed by the dial), and causing massive internal injuries. This is only used during desperate situations as Lucci is always shown panting after using it. In the FUNimation dub, this is called Rokuohgun, and in the Viz manga, this is called Six King Pistol.


 * Rokushiki Ogi: Rokuogan (六式奥義　六王銃): Used by Lucci. This is the ultimate Rokushiki technique that can damage an opponent internally, similar to the Impact Dial, or of equal or more strength to the Reject Dial, but the technique is considered to be much more powerful, and can be performed without the side effect of great pain to the user. It appears to be two fists held at close range that can damage the opponent with a blast powerful enough to cause even Luffy to cough up blood and come close to death. In the Viz Manga, this is called Six Powers Supreme Six King Pistol.


 * Sai Dai Rin: Rokuogan (最大輪　六王銃): Used by Lucci in his half-human half-leopard form which gives him the advantage of having a tail which is used to immobilize an opponent if they attempt to escape it, this technique is used in the same way as Rokuougan, except now with a larger attack radius and greater attack power. The move is so powerful that the shock wave it sends out can punch a hole in rock even after going through its intended target, similar to Bartholomew Kuma's Pad Hō technique. In the Viz Manga, this is called Ultimate Radius Six King Pistol.

Trivia

 * The Rokuogan resembles the One Inch Punch, popularized by Bruce Lee (but invented centuries ago by Chinese martial artists).
 * While facing Enel, Luffy essentially used Kami-e to evade his attacks, due to his rubbery body.
 * Tekkai is similar to Busoshoku Haki, as both reinforce the users body in some way, the difference being that Haki is based on the user's willpower and Tekkai is based on the user's physical power.
 * Tekkai also appears to be based on the Iron Shirt technique in Chinese martial arts.
 * The Shigan technique is most likely a reference to the Shaolin Monks' fictional technique: Shaolin Finger Jab.

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