A (Fourth Raikage)

is the of Kumogakure as well as the Supreme Leader of the Shinobi Alliance. He is also the older brother of Killer Bee, the jinchūriki of the Eight-Tailed Giant Ox. As it is hinted that Killer Bee is a member of the Yotsuki clan, A is likely a member, as well. Knowing Yugito Nii's and Killer Bee's immense powers if they were to ever transform into their full tailed beast forms, he forbade at least Killer Bee from doing so.

Background
While little is known about his track record as a shinobi, it was shown that he was part of the Third Raikage's special team tasked to hunt and subdue the Eight-Tailed Giant Ox when its past jinchūriki was unable to control it, unleashing a rampage. He was responsible for cutting off one of the Eight-Tails' four horns.

The level of trust the village had for him is apparent, such as how he is shown backing the Third Raikage up to deal with the Ox during one of the rampages, standing right beside him for most of it. The fact his brother Killer Bee was chosen to be the Ox's new jinchūriki suggests he was already intended to be the next Raikage (as per the tradition of having jinchūriki with close bonds to the Kage).

Appearance
A has a lot of similarities with his younger brother. He is a tall dark-skinned man with a large muscular build, slicked-back white hair, a few wrinkles, his top lip also has a darker hue than the bottom one similar to his younger brother and a small mustache and beard. He has lost his left forearm from just under the elbow due to his left arm being burned by Amaterasu's flames.

Unlike other Kage, A seems to wear his Kage cloak and hat on a regular basis, without a shirt underneath which further displays his hulking physique. He has black shuriken tattooed on both shoulders. On each wrist he has gold bangle bracelets, which seems to have protrusions that can jut out when he attacks, and has a gold belt on his waist with a boar's face engraved in the center. All of these aspects combined give him the appearance of a professional wrestler.

Personality
He is very caring and protective towards his younger brother, despite Killer Bee's status as a jinchūriki, and wept at the idea of his younger brother being captured by Akatsuki. However, when Killer Bee's ploy to use the affair to have a vacation was discovered, A was furious, and swore to punish his little brother for it.

He is also headstrong and easily excited, smashing a desk apart when news of his brother being captured arrived. He also burst through a palace wall (probably from inside his own office too) to attend the Kage Summit. His assistant implied that this wasn't the first time, suggesting that he is quite destructive while in this mental state.

He also has a very stern and decisive personality, seemingly unaffected by Naruto's pleas for Sasuke's life. In his eyes, respect and strength mean everything in the ninja world, believing that the weak should and will be crushed. This correlates with his philosophy that a ninja should never compromise or bow down in front of another ninja. A has also been shown to be very suspicious of the other ninja villages, accusing all of them of working with Akatsuki and questioning their loyalties.

In battle, A is shown to be physically brutal, as he uses extreme physical force to devastate his opponents, and is willing to sacrifice a limb, rather than lose a chance to defeat his opponents.

When he learned his brother was alive, his attitude had mostly calmed down since his first appearance. He spoke with civility with the other members of the Alliance, as well as keeping his cool during Tsunade's outburst.

Abilities
As the Raikage of Kumogakure and Supreme Leader of the Shinobi Alliance, A is undoubtedly a powerful shinobi. His younger brother Killer Bee also mentioned in his fight with Sasuke that, before him, only A was able to deflect the Eight-Tails. Karin notes that his chakra level is comparable to that of a tailed beast. A's signature fighting style is to combine his taijutsu and ninjutsu to form the powerful nintaijutsu, which was able to break through Sasuke's Amaterasu coated Susanoo bones.

Taijutsu
A uses a 'power' type fighting style. He possesses a great deal of physical strength, as he first appeared lifting a large amount of weight with just one hand, and broke his desk with a single punch. His strength is further displayed at the Five Kage summit when he punches through a wall, the floor, and even snapped Suigetsu's sword in two (albeit the sword already had a partial crack in it from Suigetsu's duel with Killer Bee). A was also able to punch a hole in Jūgo's arm and chest with ease, despite the latter being armored with his Level 2 Cursed Seal form. He was also able to cut through one of the four horns of Eight-Tailed Giant Ox when it was being subdued thirty years prior with his physical strength and Lightning Release Armor.

Despite his large physique, the Raikage is noted for being very fast, grabbing Zetsu's throat before he had a chance to react. Befitting his appearance, the Raikage seems to prefer taijutsu combat to which he has shown tremendous prowess at. In addition to powerful punches, he is shown able to use equally impressive throws and take-downs. He prefers using wrestling techniques to more traditional forms of taijutsu.

He is shown to have an immense tolerance for pain, as he was able to withstand having his arm set on fire by Amaterasu and cutting it off without flinching.

Lightning Techniques
On top of his physical capabilities, A is also skilled in lightning-based jutsu, releasing a continuous surge of electricity from his body when confronting Sasuke. This electricity acts as a compliment to A's natural physical strength and speed to the point where he claims not even the Sharingan should be able to keep up with his movements, as such he is a master of Nintaijutsu. This is due to electricity stimulating his nervous system and speeding up his neural synapses, amplifying his reflexes. While using this ability, he is able to dodge Jūgo's multiple chakra blast and Amaterasu, both at point blank range. His speed in this state is greatly increased, to the point that it was mentioned by C that the Raikage's nervous system and reaction speed becomes comparable to that of the Fourth Hokage, Minato Namikaze.

The electricity can also work as a powerful defense. By momentarily increasing the electrical surge, A was able to deflect a strike from Sasuke's Kusanagi Sword: Chidori Katana from behind and receive only a minor wound on his chest from a direct Chidori strike. While combining his lightning power with the full force of his chakra, just its sheer energy is strong enough to demolish all matter around him.

He has also shown the ability to focus lightning chakra into a point sharp enough to neatly cut through human limbs.

Invasion of Pain Arc
A was first seen enraged by news of Killer Bee's capture by Akatsuki. When he learned that the culprit was Sasuke Uchiha, a missing-nin from Konoha, he complained about why the Hokage had not dealt with him, compared to how fast they had dealt with the Hyūga Incident. With Killer Bee's capture coming so soon after that of Yugito Nii, A called for a meeting of the five Kage to discuss Akatsuki. He also instructed Team Samui to inform Konoha that he will personally deal with Sasuke.

Five Kage Summit Arc
A departed for the Kage summit with two bodyguards: Darui and C. On their way to the Land of Iron they reunited with Team Samui, who provided them with information on Sasuke acquired in Konoha. C quickly discovered that Team Samui had been followed by Naruto Uzumaki. A kept his men from attacking Naruto and agreed to listen to what he had to say. Naruto pleaded for the Raikage to spare Sasuke, but his request was flatly refused and the Raikage berated him for sticking up for a criminal.

When the Kage Summit began, A quickly showed his disapproval of the other villages by smashing the table in front of him, prompting all of the bodyguards to come to their Kage's aid. After they returned to their position, A pointed out that only Kumogakure has never had an Akatsuki representative, nor has it ever employed Akatsuki for a battle. He insinuated that the current Hokage, Danzō, used Akatsuki to dispose of the Third Hokage and the Fourth Kazekage. When Danzō was nominated to lead a joint task force to deal with Akatsuki, A was outraged. Before he could raise much of an objection, however, White Zetsu appeared and told those in attendance that Sasuke was nearby.

After getting rid of White Zetsu, A and his bodyguards immediately mobilized to go after Sasuke, and were drawn to Taka's battle with the Land of Iron's samurai. When C told him that Sasuke's chakra was straight below them, the Raikage burst through the floor where they encountered Sasuke and his team. A easily destroyed Suigetsu's sword and caused Jūgo to transform into the second stage of his Cursed Seal in order to fight him. Although Jūgo initially appeared to have the advantage, A was able to punch a hole through his arms and into his chest and evade his attacks, before finally defeating him.

Sasuke and A then began to fight. With his Lightning Release Armor, A avoided most of Sasuke's attacks, deflecting his lightning charged sword, and was barely wounded by his Chidori. He then proceeded to counter Sasuke but the assault was negated through Sasuke's use of an incomplete Susanoo to protect himself. Sasuke attacked A with Amaterasu, which he dodged. Sasuke then coated his Susanoo with Amaterasu's flames to deter additional physical attacks. In his growing rage, A ignored this and attacked through the flames, causing his left arm to ignite, but still managed to smash through the defense and hit Sasuke.

When A prepares another "final blow", Sasuke began to stage a counterattack. Before A could be further wounded, the Kazekage, Gaara, intervened, using his sand to block the attacks. A was angered by the interruption, but Gaara stated that continuing his attack would only cause additional injury. Gaara then began to speak to Sasuke. While waiting for Gaara to finish, A severed his arm and instructed C to stop the bleeding with his medical ninjutsu so that he could rejoin the battle. Sasuke then collapsed the roof with Susanoo. While the Kage and their bodyguards dodged the rubble, Sasuke escaped from the hall to find and kill Danzō. After catching up with Sasuke, A learned from Madara Uchiha that his brother was still alive, which both shocked and angered him. He realized what Bee's plan actually was and said he will punish him with his "Iron Claw".

After Madara revealed his "Eye of the Moon Plan", the Kage refused to surrender Killer Bee and Naruto to the Akatsuki. Madara then declared the start of the Fourth Great Shinobi World War and disappeared. The need of an alliance between the Five Great Nations was then brought up again. Mifune nominated A to be the leader due to how well he had already dealt with the enemy, and because he could better control Killer Bee than anyone. After asking the other Kage, it was agreed to make him leader of the Shinobi Alliance.

A's first decision was to locate his younger brother before he would fall into the hands of Akatsuki. He and his men managed to find Killer Bee in time fighting Kisame Hoshigaki, thanks to Kisame's reckless tactics. Together, the Raikage and his younger brother decapitated Kisame with a Double Lariat, later revealed that this was not Kisame rather one of Zetsu's clones. After their victory, A angrily scolded Bee for his antics. After arriving back in Kumogakure he and the others are greeted at the gate by the villagers. His assistant said that they needed to be briefed on what happened at the Five Kage Summit.

Confining the Jinchūriki Arc
After a war planning session with Kumogakure's military forces, A ordered that the other villages be notified about a new Kage meeting in three days. At the meeting, he begins questioning their early arrival, but discussion soon begins. After a heated debate regarding whether or not the Alliance should be relocating the jinchūriki ends in the approval of such a matter, A decides that Naruto Uzumaki and Killer Bee will be sent to a refuge that he has kept in reserve. He mentions that it is appropriate that it be in Kumogakure, seeing as the village has not given rise to any Akatsuki members. The place turns out to be an isolated island where he and his younger brother used to train together intensely. After Kisame revealed the location, A refuses to have Killer Bee and Naruto to be moved from the island, since he already plotted a route for the island to move if the Akatsuki were to discover its current location.

Trivia

 * His name is the Japanese pronunciation of the English letter "A". This is similar to the names of Killer Bee, C, and J, that are the pronunciations of the letters "B," "C," and "J," respectively.
 * A is left handed.
 * Both A and the Third Raikage have a muscular body and bodybuilder-like stature. It may be conclude that he is physically strong like A.

Quotes

 * (To Naruto) "Shinobi ought not lower their heads so easily, action and power are what shinobi respect!"