Kaku is first seen as one of the five foremen of Galley-La Company's Dock One and specializes in mechanics, diagnostics, and housecalls. It was Kaku who inspected the Going Merry  and informed the Straw Hats that it was broken beyond repair. Later on, it was revealed that Kaku was a member of CP9, operating undercover in order to obtain the Pluton blueprints from Iceburg. Along with his colleagues, he has been dismissed from CP9 by Spandam.
Kaku has big black eyes with 3 eyelashes on top of his eye, and a long nose similar to Usopp's, only rectangular in shape. Due to this, several characters, such as Luffy, Sanji and Zoro have mistaken him for Usopp.
When he worked for the Galley-La Company, he wore a white cap, a high-collared orange shirt with blue sleeves, jeans and white sneakers.
In SBS volume 44 he was depicted in an SBS as a child with fluffy hair, a shorter nose (though still long by his age standards), and wore a cap backwards.
Despite his role as a villain, Kaku is surprisingly honest, even to his enemies and even more so than Fukuro, though he does not seem to take insults well. As soon as his hybrid (giraffe/human) form was mocked, he sliced the Tower of Justice in half, in a rage of embarrassment.
He also talks like an old man, as remarked by several characters, despite being only 23 years old. He uses the term "washi" (meaning I, though used mainly by elders), rather than ore (also meaning I, a masculine term used by young adults). In the FUNimation dub, he instead uses old fashion slang.
After being revealed as one of the Water 7 CP9 agents, Kaku's personality becomes rather cold and dispassionate in contrast to his character on Water 7, where he was mainly seen laughing and smiling. Despite this, he often taunts his opponents during battle, ate a Devil Fruit for the fun of it, and exclaimed "This is fun!" during his life-and-death battle with Zoro. He also seems to place a chance to fight over easy accomplishment of a mission; when Zoro and Sogeking were cuffed together, he wished to help them, so he would not be forced to share his target with Jabra. When neither agent had the key, both agreed that the prey was up for grabs.
Kaku showed great sportsmanship after his defeat where he laughed at Zoro's comment of working in a zoo. He remarked "too bad" when Zoro passed Paulie's message of "you're fired", handed over his key without Zoro having to say a word. He also appeared to be the only one of the four members undercover in Water 7 who expressed some regret that he could not go back to the way he had been living for the last five years.
Abilities and PowersEdit
Kaku is a highly intelligent and cunning individual, being able to become a master shipwright within a 5-year period merely as a form of espionage and surveillance over his "boss" Iceburg (who CP9 believed to have possession of the blueprints for the Ancient Weapon "Pluton"). He is also skilled at developing or masquerading with personalities: ranging from fun-loving and almost childish to cold and ruthless (the former seems to be his true mentality, while the latter is a product of his assassin occupation).
He is able to move incredibly fast and leap from buildings from amazing heights and distances without a scratch. During his disguise as a shipwright, Kaku uses a variety of pavers/chisels as projectile weapons (used against Luffy in Dock 1). His jumping abilities has earned him the nickname "Mountain Wind" (山風 Yamakaze?) during his time in Galley-La.
Kaku can also function as a lie detector. He demonstrated the ability to tell whether something is true or not by feeling a person's wrist and then tell the truth by determining the speed of the person's pulse.
He is a skilled and creative combatant, as despite having no previous experience with a Devil Fruit, he managed to hold off Zoro largely by making up techniques on the spot, such as folding himself into a cube, using his nose as a battering ram, or using his neck as a Rankyaku medium.
Since Kaku worked as a shipwright during his mission in Water 7, this means he has some carpentry skills. Since he was an evaluator, he has great knowledge about ships. He evaluated the Going Merry  and explained the reasons why it cannot be repaired. Like Rob Lucci, a testament of his skills is that he was able achieve them in five years while others spend their whole life growing their skills and what's more was that this was an undercover job. He was also able to recognize the real Pluton blueprints even when Franky was flipping through the pages quickly.
- Further information: Rokushiki
Kaku is proficient in all six forms of Rokushiki, but his expertise seems to be in Rankyaku, due to his many variations of the technique. With a Doriki of 2200, he is the second strongest assassin in his generation of CP9, which is said to be by far the strongest in the organization's history.
- Further information: Yontoryu
He is also the most proficient swordsman of CP9, being able to use two giant chisels as makeshift swords when he clashed with Zoro in Iceburg's room. During his battle against Zoro in Enies Lobby, Kaku revealed that he is a user of Yontoryu (四刀流 Yontōryū?, literally meaning "Four Swords Style") by using two Shirasaya katanas (or shikomizue) and both legs (with Rankyaku). He wielded both of his swords in reverse, similar to Strawberry and Doma.
- Further information: Ushi Ushi no Mi, Model: Giraffe
When he returned to Enies Lobby with Lucci, Kalifa, and Blueno, Kaku ate the Ushi Ushi no Mi, Model: Giraffe, a Zoan-class Devil Fruit given by his boss, Spandam, which allows him to transform into a giraffe-human hybrid and a full giraffe. As Kaku ate the fruit just after the Straw Hats arrived to Enies Lobby (his Devil Fruit was shown in a chest opened and belonging to Spandam), he did not have full control over it, as seen when he first showed its powers to Zoro where he accidentally transformed into full animal-form, when he intended to go animal/human-form. Jabra even laughed at the fact that he turned into a giraffe.
When in animal or animal/human-form, he can make further use of Rankyaku, as he gains two additional legs. The power of his Rankyaku is also increased, as seen when he uses Rankyaku: Amanedachi to slice through the whole tower that he and Zoro are fighting in.
His animal/human-form also has a square shaped nose and limbs, because of the shape of Kaku's nose while in human form. He can use this, together with his high speed to create a more powerful version of Shigan, the Bigan, by withdrawing his long neck into his body and then firing it at his opponent.
Kaku's new form was very unusual to him, as he was testing the new form out on Zoro. All his transformations, including the "Square Form", used the same move, and even Zoro remarked that the move Kaku was using was extremely repetitive.
Five years before the current storyline, four members of the secret organization, CP9, took guises in the city of Water 7. As part of his mission, Kaku infiltrated the Galley-La Company by applying for a job as a shipwright in the attempt to retrieve the blueprints for Pluton from Iceburg, mayor and former pupil of legendary shipwright, Tom. Kaku became famous in the Galley-La Company, known notably for jumping off tall areas, clearing massive distances, earning the nickname: "Mountain Wind" (山風 Yamakaze?). He became a respected member of the group as well. He gained the identity of a ship mechanic and diagnostic.
Water 7 SagaEdit
Water 7 ArcEdit
When the Straw Hat Pirates arrived at Water 7, they needed repairs to their ship. However, due to a tipping off from Admiral Aokiji, an opportunity in the form of "Demon Child" Nico Robin presented itself. Using the threat of a Buster Call attack, they blackmailed her to give a fake assassination attempt on Iceburg's life to frame the Straw Hats and leave them to be taken to Enies Lobby. When the Straw Hats pleaded for Galley-La Company to fix the Going Merry, Iceburg asked Kaku to perform a diagnostic on the ship, which he complied. After returning, Kaku confirmed that the ship was irreparable due to a broken keel and would have no chance in reaching the next island.
At nighttime, CP9 made an "attempt" on Iceburg's life and framed the Straw-Hats. Believing that the pirates were the criminals, the Galley-La company attacked Luffy while he was fighting Franky the next morning. During the fight, Franky called Kaku Yamazaru ("Mountain Monkey") to mock him and used Coup de Vent against Luffy and the Galley-La foremen. When evening arrived, the CP9 group initiated their plan to steal the Pluton blueprints and invaded Iceburg's mansion while wearing disguises. Kaku and Lucci pretended to be defeated by the assailants by using two of the defeated foremen to wear their clothing. Once they cornered Iceburg, they interrogated him and realized that the blueprints were not with Iceburg, but they deduced that they were with Franky by reading Iceburg's pulse. Before they could kill Iceburg, Luffy, Paulie, Zoro, Nami, and Chopper arrived to confront them. During the ensuing clash, Zoro asked Kaku if his diagnosis on the Going Merry was a lie. Kaku reiterated that although his Water 7 guise was false, his analysis was genuine and the ship could not sail. Kaku and his fellow agents displayed their fighting techniques and overpowered their opponents. Having decided to leave no evidence of their attack and their identities, they set Iceburg's mansion on fire, hoping to kill him in it, and left the Straw Hats to take the fall.
After discovering Franky's secret hideout, they quickly went there and subdued Franky. Kaku sent the Going Merry into the midst of the Aqua Laguna and to its apparent demise. After capturing Franky and Usopp, they set out for Enies Lobby on the Puffing Tom.
On the way to Enies Lobby, CP9 encountered some complications when Sanji stowed away on the Puffing Tom and initiated his own rescue operation. He managed to free Franky and Usopp and they attempted to retrieve Robin. Despite Sanji's best efforts, CP9 prevented Robin's escape and recaptured Franky.
Enies Lobby ArcEdit
Eventually, the CP9 agents arrived at Enies Lobby with Robin and Franky. At the Tower of Justice, they met up with the other members that they had not seen in years and their boss, Spandam. Fukuro then tested the others' Doriki and revealed that Kaku had a level of 2200. He and Kalifa were later given Devil Fruits by Spandam and under the urging of Lucci, they proceeded with eating them.
When they heard that the Straw Hats, the Franky Family, and their Galley-La allies started attacking Enies Lobby, the CP9 agents (except Blueno) stood at the balcony and saw Luffy standing on the roof of the courthouse, having emerged victorious from his fight with Blueno. After the rest of the Straw Hats arrived at Luffy's location, Franky revealed that he had been carrying the Pluton blueprints all along and the CP9 agents could only watch as he burned the blueprints in Spandam's face. After Spandam pushed Franky off the balcony, the CP9 agents witnessed Franky and the Straw Hats entering the Tower of Justice with some assistance.
After the Straw Hats split to find the key to Robin's Seastone handcuffs, Zoro came across Kaku and the two quickly battled each other with Kaku revealing his own sword-fighting style. Later in the fight, Kaku ended up causing the floor to cave in by transforming into his full giraffe form instead of his half-giraffe form. The two fell into the room where Sogeking and Jabra were fighting, and were involved in their fight as well. Jabra started to break out in uncontrollable laughter after seeing Kaku's full giraffe form. Kaku managed to transform into his half-giraffe form, but this only made Jabra laugh more hysterically and made Sogeking accidentally handcuff himself and Zoro together.
All this mocking eventually got to Kaku and in his anger, he used an attack that sliced the tower in half where it remained lopsided. After a bit of arguing with Jabra on whose prey was whose, they offered to help separate Sogeking and Zoro from their handcuffs by using their keys. However, neither had the appropriate key and the two agreed to work together to defeat the pirates and escape the oncoming Buster Call, which was accidentally initiated by Spandam. Zoro managed to hold them at bay by using Usopp as a sword (moreover having Usopp hold one of his swords while he used Usopp like a hilt) until Nami freed them of their handcuffs.
As Zoro and Kaku continued their one-on-one match, it seemed that Kaku had the upper hand thanks to improvising with his Devil Fruit and his swordplay until he was defeated by Zoro activating a new power called Asura. Zoro then passed on a message from Paulie to CP9, telling Kaku that he and the rest of CP9 were fired. Kaku expressed regret that he could no longer be a shipwright and that he genuinely enjoyed the profession. Zoro jokingly responded that he would always have the zoo. He laughed and gave Zoro his key before passing out. Kaku's key was the final key to be obtained by the Straw Hats and also the key to Robin's handcuffs.
CP9's Independent ReportEdit
He appears on the third cover in the report, sitting, and apparently severely injured, having been carried by Jabra along the Sea Train tracks.He had arrived at St. Poplar and is shown pretending to be a "giraffe slide" while in his full giraffe form for children to ride, in an effort to help CP9 raise money for Rob Lucci's medical bills.
Afterwards, he was at a café with Fukuro, Blueno, and Jabra waiting for Kalifa and Kumadori to return with the shopping, he along with Fukuro is laughing at Jabra.
Later, he is seen as the scorekeeper while the others are bowling. However, their bowling match is interfered when the Candy Pirates ransack the island, so he and the rest of CP9 quickly dispatch them on their ship. Kaku was shown fly-kicking one of the pirates as the crowds cheered. However, since Lucci crushed the skull of the captain, the crowd was horrified and the CP9 realized they cannot stay in St. Poplar, so they sail off to their homeland, where they watch a new generation of CP9 being trained. Captain Very Good arrives to capture them, but they refuse to let him disturb their old home.
As the CP9 battled, and eventually defeated the Marine troops led by Very Good, Lucci contacted a physically crippled Spandam using a Den Den Mushi, and promised to come for him very soon. With that CP9 began their aim to eliminate their former director by leaving their homeland and setting sail.
- Galley La vs. Big Helmet Pirates
- Kaku, Rob Lucci, Tilestone, Peeply Lulu, and Paulie vs. Monkey D. Luffy and Franky
- Kaku vs. Roronoa Zoro (Galley La Headquarters)
- Kaku and Jabra vs. Zoro and Usopp
- Kaku vs. Zoro (Tower of Justice)
- CP9 vs. Candy Pirates
- CP9 vs. Very Good's crew
Early One PieceEdit
An early design of Kaku had him with a normal nose rather than his long rectangular nose.
Also, in One Piece Green: Secret Pieces, it is revealed that he was supposed to fight Sanji instead of Zoro and partly Sogeking.
Translation and Dub IssuesEdit
Kaku's name most likely comes from the Japanese word "kaku" (角 kaku?, literally meaning "angle", but also means "horn" if read as "tsuno"), a reference to his rectangular nose along with its length.
Although Kaku is 23 years old, he speaks as if he were much older, as he adds the suffix "-ja" to most of his sentences. "-ja" is commonly used amongst old men. He also uses "washi", a term of addressing oneself used by old men.
In the FUNimation dub, to match the "old man" style of talking, he uses old fashioned expressions such as "two shakes of a lamb's tail" or words like "skedaddle".
- One Piece: Unlimited Adventure
- One Piece: Unlimited Cruise
- One Piece: Gear Spirit
- One Piece Thousand Storm
- One Piece Dance Battle
- One Piece: Pirates Carnival
- One Piece Romance Dawn: The Dawn of the Adventure
- One Piece: Pirate Warriors
- One Piece: Pirate Warriors 2
- One Piece: Pirate Warriors 3
- One Piece: Gigant Battle
- One Piece: Gigant Battle! 2 New World
- One Piece: Pirate Warriors 2
- One Piece: Pirate Warriors 3
- Zoro giving Kaku Paulie's "you're fired" message is a pun on Kaku's giraffe theme; "kubi" (首 kubi?), the Japanese word used for "fired", can also mean "neck".
- Kaku's birthday was revealed in a Volume 43 SBS to be August 7. This is because in Japanese, 8 can be pronounced as ha, and 7 can be pronounced as na. Put together, these make hana, the Japanese word for nose in reference to his long, rectangular nose.
- Kaku ranked at 45th place in the 5th Japanese popularity contest, making him the second most popular CP9 member.
- Kaku's key was the one that worked on Robin's handcuffs.
- When CP-0 came to Dressrosa a second time, Rob Lucci talked to a man with Kaku's speech pattern. In the anime, the CP-0 member was directly shown to be Kaku, although this revelation is non-canon.