Killer B

is a shinobi from Kumogakure and the jinchūriki of the Eight-Tails.

Background
At a young age, B along with several other children were gathered in order to select a tag partner for A. Out of all the children gathered, B was the only person able to successfully perform the Double Lariat with A. As such he was given the name "B", and A stated they would be brothers from that day on. Since the age of five, B has been best friends with Motoi, whom he always greeted with a fist bump. After the his cousin, the jinchūriki of the Eight-Tails lost control and killed Motoi's father, B was chosen as its next jinchūriki. Soon afterwards, B suffered from similar prejudices against jinchūriki, not too different from that the villagers of Konohagakure and Sunagakure had against Naruto Uzumaki and Gaara respectively.

However, he kept smiling and pushed himself to be the best jinchūriki that he could be, so that his brother wouldn't be hurt politically as the Fourth Raikage. After his father's death, Motoi tried to kill B, believing it would also kill the Eight-Tails and avenge his father, but B disarmed him easily, and despite the attempt on his life, bore him no ill will, which led Motoi to not speak to B for thirty years out of shame. B would later train with his brother on an island in the Land of Lightning, where there he would find the Falls of Truth. There he learned how to control the Eight-Tails in the blink of an eye. Some time after his training, B, alongside A, and other Kumo shinobi confronted Minato Namikaze and his small squad. When Minato moved to counter A's attack, B used a tentacle to push A out of the way, causing shock to the Konoha shinobi that he was the Eight-Tails' jinchūriki. Some time since then, much like Naruto, B has become beloved in Kumo as the village's hero, or, as Motoi called him, the "Hero of Heroes".

Appearance
Killer B has dark-skin and possesses a muscular build, as well as white hair (blond in the anime) and a goatee. On his right shoulder, he has a tattoo of the kanji for, which is the Iron Armour Seal that was used to seal the Eight-Tails into him, and on his left cheek, he has a tattoo of a bull's horn (correspondingly, the Eight-Tails has horns like a bull, and the left one is partially missing). His top lip also has a slightly darker hue than his bottom one.

Killer B wears oval shaped sunglasses and a white coloured forehead protector. He also his village's standard one-strap-over-one-shoulder flak jacket, and a long, red rope belt tied around his waist, the standard Kumo hand and shin guards, shinobi sandals, and a white scarf around his neck. He originally carried seven swords on his back, but now only carries two swords along with Samehada.

Personality
Killer B is very proud of his own power, and like Naruto Uzumaki, has great overconfidence and can be quite cocky and stubborn, especially in terms of his own strength, demanding respect from others and asks to be called and his tailed beast be called. B has a special way of expressing his pride through song, more specifically in rap-style. He will even write his rhymes in the middle of a fight, or during an important meeting, even if they are no good. This sometimes causes the people around him to become greatly bothered by him. B doesn't respect anyone who would make fun of rap or his lyrics.

The Raikage has noted that Killer B is not the type of person to work with the strategies created by people and that he would only bring chaos into a battlefield. The Raikage also notes that he is the only being that B will listen to, as he is able to keep him in check. Despite all this, B knows talent when he sees it, and respects those with it. The primary example is his fellow Kumo jinchūriki, Yugito Nii, who he looked up to for her extreme skills. He had also praised Sasuke after their fight, stating he was one of the strongest shinobi he had ever fought. B has a very close relationship with his older brother, the Raikage. According to Motoi, the reason behind him becoming a jinchūriki was for the sake of his brother, even if it meant being shunned by the villagers. He didn't complain, and was always cheerful and determined.

Killer B seems to wish to leave his village for a vacation due to being tired of being the guardian and he can also be very lazy and not much of a hard worker, ready to transform into his full Eight-Tails form and fake his defeat and capture, only to escape from his village for a "vacation". When the Fourth Raikage, Darui and C learned that B was not captured by Akatsuki, they immediately guessed his intentions and were not surprised by it, though they were very displeased.

However, when someone close to him is in danger, Killer B has no qualms about putting himself at risk to save them, if necessary, as seen when he prioritized the safety of his singing master Sabu and his pet, Ponta, first over confronting Kisame head-on when the Akatsuki confronted his entourage. This caring nature differs him from a typical jinchūriki, most of whom are cynical and uncaring towards others. However, it was hinted that his past as a jinchūriki may not have been unlike Naruto's, since Motoi claimed that being a fellow host, B understands what Naruto went through. He has a casual relationship with the Eight-Tails, frequently engaging in friendly conversation with it, even sitting upon its nose at one time. He was also completely unaffected by Naruto's Harem Technique, resisting lustful advances and even appearing indifferent. Naruto stated that B is the first man to resist this technique. However, he is not completely unaffected by such things, as he noticed Tsunade's rather sizable cleavage, which his brother reprimanded him for.

B is also very kind and compassionate, having befriended all the giant animals on the Island Turtle which may indicate that he has a liking for animals, as well as never expressing any ill will towards Motoi who tried to take his life, nor against the villagers who used to shun him.

Abilities
As the guardian of Kumo and jinchūriki of the Eight-Tails, Killer B is an extremely powerful ninja, capable of overwhelming the entire Team Taka all by himself, and has had his skills praised by several Kumo-nin, including his older brother. Madara Uchiha claimed that he is the perfect host, a statement later reaffirmed by Kisame. Similar to how other jinchūriki obtain physical traits from their inner demon, B is able to produce ink from his mouth, which he mainly uses to write lyrics when he is lacking of regular writing tools or to blind his opponent. As expected of a jinchūriki, B has a very large reservoir of chakra, enough to make Samehada get very excited and turn against Kisame. During his time on an island where he trained to control the Eight-Tails, B tamed almost all of the island's beasts. A claimed that B had more talent than he did. B is at least knowledgeable enough of seals to know that Naruto's Four Symbols Seal is better than his own Iron Armour Seal.

Killer B has shown the ability to think on the fly, as shown when he used the Body Replacement Technique to switch places with the Eight-Tails' tentacle so he could escape Sasuke Uchiha's Amaterasu. He has also demonstrated the ability to interpret someone's "heart" as well as transmit his own feelings merely through touching someone (which is usually done through a fist bump). This ability was first demonstrated when he was training with Naruto in the Tailed Beast Temple, again when Iruka expressed his wishes to protect Naruto to him and when he stopped his brother from attacking Naruto.

Taijutsu
B possesses immense physical strength and combat prowess, capable of disarming a skilled opponent like Suigetsu with his bare hands, and winning a sumō match against a giant bear. Even as a young boy, he was the the only person to successfully perform a Double Lariat with A, allowing him to become the future Raikage's tag-team partner. He has shown incredibly fast reflexes, enough to intercept Minato Namikaze's Flying Thunder God Kunai with one of the Eight-Tails' tentacles just as he was about to stab A after using he using the Flying Thunder God Technique. His speed is great enough that when Jūgo attacked him, he was able to make it to another mountain's peak before Taka could react, requiring Karin to locate him. He is incredibly durable in battle, having received a solid kick to the neck from Sasuke Uchiha only to drop his sword and begin writing lyrics, escaping unscathed after being hit by the electricity of Sasuke's Chidori, and blasted from behind with a powerful punch from Jūgo. Killer B has a fighting style which is similar to that of the Raikage's because they both use wrestling moves instead of standard taijutsu. He supplements the speed and power of his taijutsu with his tailed beast's cloak.

Kenjutsu
While originally only carrying two swords when he was young, B has developed his swordplay to an incredible level. Possessing a unique fighting style, B holds his seven blades in between the joints of his arms (left armpit, both elbows), right leg, stomach, the right side of his neck, and in his mouth. As strange as it appears, B is very skilled with this. Because of the unpredictability of his movements, his opponents are easily overwhelmed with all of the varying swings, giving him great versatility very similar to hip-hop dance. When he finds an opening, B can impale his opponent with most of his swords quickly and simultaneously. Neither Suigetsu nor Sasuke could read his sword work, despite the former being a highly trained swordsman and the latter having the Sharingan. He is also capable of cutting through almost anything when he flows his lightning chakra through his blades. He can also use these blades as mid-range projectiles, and coat them with lightning chakra to slice right through the target. By covering himself with the Eight-Tails' chakra, he creates an "Eighth" sword.

Samehada betrays Kisame due to B's high chakra level, and B intended to use it as his main weapon, unaware that Kisame was able to hide within the monstrous blade itself, although it returned to him, after Kisame was exposed.

Nature Transformation
During the battle with Sasuke he displayed the ability to flow lightning-natured chakra through his blades to increase their cutting power, similar to Sasuke's own jutsu. Killer B's prowess in Lightning Release techniques is so great, he can charge a sharp but weak pencil-point to pierce straight through a large tree trunk and even through the ground. As stated by Kisame, B is able to do this by increasing the vibration frequency of his lightning chakra to surpass the standard penetrative force of wind chakra.

Jinchūriki Transformations
Killer B has full control over his tailed beast, something which few others have been able to accomplish. Like other jinchūriki, B has the ability to create a chakra cloak by drawing on part of his demon's power. He can then form this chakra into the form of two horns, and use them to attack the enemy with a technique called Lariat. This attack has incredible speed and power, but the linearity of his movements makes him easier to predict. Because he has a strong relationship with his own tailed beast, it acts as his partner in battle, disturbing his chakra to dispel even genjutsu from Mangekyō Sharingan.

Like his fellow Kumo-nin, Yugito Nii, B is able to become his tailed beast with great ease. Unlike her, however, he can retain complete control even in this fully released state. He can also partially transform parts of his chakra shroud into parts of the Eight-Tails' body. When fully transformed, he can easily fire a Tailed Beast Ball many times the size of its already giant body, but B was forbidden from transforming by A. B makes it a point to ignore this order when he can, either when training or to fight formidable opponents.

His control over his forms is so great, he can form all eight tentacles on his back without a cloak, and use them to balance various blocks perfectly, and form one of his arms into the Eight-Tails' arm and fist.

Invasion of Pain Arc
Taka tracks Killer B to the Valley of Clouds and Lightning soon after he finishes training with his tailed beast. When Suigetsu attacked him, he easily overpowered him, and uses Suigetsu's sword to defeat Jūgo afterwards. Later when Sasuke Uchiha confronts him, he shows an unorthodox sword style where he manages to hold all seven of his swords in a rather awkward pose; this is deceiving as his seven sword style is extremely formidable and he even mortally wounds Sasuke as he was unable to track the swords even with his Sharingan. This would in fact have been a fatal hit, but B mentions that Sasuke had channelled lightning-nature chakra through his body to avoid a fatal hit.

As he moves in to finish Sasuke, Suigetsu comes to save him while Jūgo attacks from behind. Even while the three fighting him at once B appears unfazed by their attacks and quickly moves away from their location. Finally getting annoyed with Taka, B announces he will unveil the. B formed his own demon chakra shield and proceeded to attack Taka. Sasuke then placed him in a genjutsu but B was able to break it with assistance from the Eight-Tails. B then struck Sasuke while his guard was down. In the end, he blasted a hole in Sasuke's chest and neck taking the surrounding organs along with it; claiming that a jinchūriki that has full control of his beast can become immune to genjutsu. He then completely released the full power of the Eight-Tails, ordering the team to cower in fear of him.

Sasuke then hit the Eight-Tails with Amaterasu. As one of its tails was about to fall on Karin, Sasuke cut it with Chidori Sharp Spear. B disguised himself as the cut part of the tail and escaped. The Eight-Tails transformed into an unconscious form of B. With his defeat, Sasuke carries him away. When his brother, A, learns of his capture, he makes plans to deal with Sasuke and the Akatsuki. When the Akatsuki later tries to extract the Eight-Tails from B's body, they find that it is only one of the beast's tentacles disguised as B. He had made the appearance that he was captured to escape his village, where he had grown bored of being a guardian. Since his village believed him to be captured, he used that as an opportunity to take a "vacation" from being a guardian. As Eight-Tails commented that a new era was coming, B thought he means about his new music career.

Five Kage Summit Arc
Killer B is shown to be near a far off mountain practicing his music career with his seemingly new music teacher, Master Sabu, who thinks B lacks passion in his singing. Later, B is approached by Kisame Hoshigaki saying his Samehada tracked his powerful chakra scent. B says he'll make quick work of Kisame. Though much to B's shock, all of his lightning techniques fail against Kisame as Samehada continues to eat all the chakra that gets close enough, even his demon chakra. Eventually, Kisame has Samehada unleash its true form.

Later as the battle progresses, B uses the Eight-Tail's chakra to transform into a eight-tailed version of the Eight-Tails, similar to a Naruto's six-tailed form along with the skeleton of an ox. B then uses the Lariat technique on Kisame severely injuring him to the point of exposing Kisame's ribcage, while Samehada absorbs the Eight-Tails' chakra. Kisame then uses Samehada to heal himself and combines with Samehada transforming himself into a monstrous shark-like form. B continues to fight Kisame and eventually gets a head on attack from Kisame in which he partially transforms one of his tails into a Octopus tail and wraps Kisame in it.

When Kisame tried to slice off Killer B's legs after he was rendered unconscious, Samehada dug itself into the ground to prevent that from happening. It also attacked Kisame to protect B as it has grown fond of his octopus chakra. B then regained consciousness after obtaining some chakra from Samehada, but still appears to be in a weakened state. Kisame kicks Samehada aside and prepares to sever B's legs with one of his own swords. After another failed attempt to kill Kisame with the pencil he threw at him earlier, B was saved by his brother, the Raikage, C and Darui. B and his brother then finish off "Kisame" by performing a Double Lariat to decapitate him. After that, B got reprimanded by A for running away from the village.

When they returned to Kumogakure, they were greeted by the villagers at the main gate. He was also greeted by his students, Omoi and Karui and showed off Samehada to them unaware that the real Kisame was hiding in the sword.

Confining the Jinchūriki Arc
B took part in a war meeting at Kumo, but didn't pay much attention to it, trying to find new rhymes instead. At a meeting of the Kage it was decided that the remaining jinchūriki were to be held on a remote island in the Land of Lightning. When Naruto and some other ninja arrived at the island they were attacked by a giant squid, but were then saved by B. On the way to the lodgings, they met a giant gorilla, which turned out to have been tamed by B, along with the other animals on the island. After everyone has settled, Naruto tried to get B to train him, but B refused because he's "on vacation." Naruto made some progress when B approved his rhyming and bumped fists with him, but Naruto accidentally insulted B while rapping. Naruto tried to use the Harem Technique, but with no results. B is later seen winning a match against a giant bear named Kintoki. Afterwards, the Eight-Tails asked B why he didn't want to help train Naruto. B answered that he doesn't like anyone who would make a fool out of his rap, however, he also hinted there was another more personal reason for not helping him. Later B saved Motoi from the giant squid, and reaffirmed their friendship. After Naruto came to terms with his inner hatred, B agreed to teach Naruto how to control his tailed beast, and lead both Naruto and Yamato to a special room within the secret temple behind the Falls of Truth, where Naruto would fight the Nine-Tailed Demon Fox.

When Naruto opened his seal and released the Nine-Tails, B attempted to help by holding it down with the Eight-Tails' chakra, but failed to do so, as he couldn't use his powers to their fullest extent within Naruto's subconscious. As Naruto's attempts continued, B used the last of his power to absorb a Tailed Beast Ball from the Nine-Tails, before being knocked out of the fight. When Naruto's transformation stopped, B asked Yamato if he did anything, who said he didn't do anything. After Naruto claimed success, he and B fist-bumped, and communicate in a way that annoyed Yamato. When Naruto revealed Kisame's presence in Samehada, B was confused, because he remembered decapitating Kisame, and was told that it was a special kind of clone. When Naruto was stuck on a wall after wounding Kisame, B followed him and exited the Falls of Truth in time to see Guy sending Kisame flying violently.

He later reunited with Samehada only for Kisame to take advantage of its affection and steal most of B's chakra. As he fled, Killer B was able to use his remaining chakra to help Might Guy give chase. After Kisame was defeated, B rapped about Guy's skills. Then after Kisame's suicide, B comforted a grieving Samehada. When Guy tried seeing what information Kisame had, a trap was activated, immobilizing them in the Water Prison Technique. After freeing himself, B tried to get to the shark, but was unsuccessful. He was also seen 'poking' Might Guy afterwards.

Shinobi World War Arc
Later, Killer B helped Naruto, Yamato, and Aoba Yamashiro evacuate all the animals into the Island Turtle's shell. He seemed to know what was really going on, and helped distract Naruto the best he could, and then started teaching Naruto how to control his Nine-Tails Chakra Mode properly by stacking several giant stone blocks with only his chakra arms.

After Naruto mastered that exercise, the next part of his training began: learning how to use the Tailed Beast Ball. Transforming into the Eight-Tails, he explained to Naruto how to transform fully into the Nine-Tails, however all Naruto could accomplish was transforming into a smaller form. Finally, after seeing how Naruto created the Rasengan, B claimed he could work on the Rasengan, noting its similarity to the Tailed Beast Ball, which Naruto exclaimed he was ready to do. B then stayed, watching Naruto train and telling him when he got the ratio correct. During their training Naruto suddenly sensed the Nine-Tails' chakra within the rampaging six-tailed Kinkaku far away from the temple. Wanting to investigate, Naruto was able to trick B into letting him out.

After Naruto escaped from the temple, B goes outside as well and spoke with Iruka, who asked B to protect Naruto. B soon followed Naruto and managed to catch up with him. B fully transformed into the Eight-Tails and fired a Tailed Beast Ball at the barrier surrounding the island. Naruto then entered his Nine-Tails Chakra Mode and propels the ball through the barriers, while B followed through with him. After they managed to break the barriers and continue to travel to the battlefield, Killer B noted comically that even though Naruto was risking his life heading to the battlefield that he was lighting up the way in his Nine-Tails Chakra Mode. The Eight-Tails then told B that it didn't care if B wanted to use Naruto as a flashlight but he should make sure not to fall behind. Later, while en route to the battlefield, they are confronted by A and Tsunade. While Naruto expressed shock at seeing Tsunade all B could utter was "No brassiere" in reference to Tsunade's bust. He was then reprimanded by his brother, but B claimed that he meant to say "brother" but misspoke.

As his brother angrily declared to him that we will not allow them to pass, B told his brother that he promised to keep an eye on Naruto. As Naruto and the Raikage start arguing, B remembered what he saw in Naruto's subconscious during his training with him. As the Raikage and Naruto prepare to attack, B intercepted A's fist and exclaimed that if he was prepared to kill Naruto, then the same would go for him. He then stated that he was ready to sacrifice his own life to ensure that Naruto got to the battlefield. Enraged, A reminded him that as a jinchūriki, their lives were not their own to control, but B stated that even so there were feelings that he, as an individual, could not discard. He then fist bumped his brother, transferring his "feelings" to him and A remembered the time when B was chosen to be his brother.

Trivia

 * Bī is the Japanese pronunciation of the letter "B" (as well as the Japanese pronunciation of "Bee"). This parallels the names of A, C, and J.
 * He quoted Muhammad Ali's famous line, "float like a butterfly, sting like a bee".
 * Killer B makes various references to bees. This is a pun on the number of tails his tailed beast has. Eight in Japanese is, a homophone to the Japanese word for bee,.
 * Though not confirmed, Killer B was given the name of Kira Hachi by fans. It comes from the word "Kirābī" incorrectly translated into Japanese (Hachi is the Japanese word for "bee", as well as "Eight". Kira is a loanword of the English "killer"). Kira Hachi, can be translated to "Killer Eight", following the homophone of bee.
 * The nickname of this character may be a reference to The Killer Bees, a professional wrestling team in the World Wrestling Federation. Additionally, the Double Lariat resembles the "Cross Bomber" move used by the Hell's Missionaries tag-team in Kinnikuman, a wrestling manga.

Quotes

 * "I'm the only one who gets to interrupt me!"
 * "I've got energy to spare and sparkling charm. The Eight-Tailed Beast's a killer bee rockin' the melody! OH YEAH!"