A is the son of the Third Raikage. At some point in the past, a group of children were gathered in order to determine who would be A's tag-partner in keeping with a long-standing Kumogakure tradition of the Raikage having a tag-team partner. Only one child was able to successfully match A's power and use the Double Lariat on a training dummy.
As a result, that child was given the name "B", and A stated that they would be brothers from that day on. He and B would eventually be teamed together on a mission with A's cousin, the jinchūriki of the Eight-Tails. While on the mission, he told A that Killer B would need something to fill the void that would be created if he was chosen as the beast's next jinchūriki.
Some time later A's cousin lost control of the beast and it went on a rampage. A was made part of a special team tasked with subduing the rampaging Eight-Tails. When the beast impaled Motoi's father with its horn, A cut it off. After B became the beast's jinchūriki, A, remembering what his cousin had said to him, tried his best to fill that apparent void.
Sometime during a conflict involving Konoha and Kumo, A would clash with Minato Namikaze for the first time. Before Minato retreated he recognised Killer B as the jinchūriki of the Eight-Tails and told A that next time they met it would be to put the title of "Kage" on the line and also offered A the advice of making sure his brother knew who he was before becoming neither human nor jinchūriki. They would clash many more times after that. A was once even told by Jiraiya that he believed Minato was the "Child of Prophecy". When A's father died, he inherited the title of Raikage. Afterwards, he forbade B's continued training in the Lariat and ordered him to complete his training in the Tailed Beast Ball at the Valley of Clouds and Lightning and restricted him to the confines of the village. At some point, he forbade B from fully transforming into his tailed beast due to its extreme power.
In the anime, after an encounter with the Nokizaru Group, A crossed paths with Tsunade and requested her services in removing the Exploding Insects implanted in both him and one of his followers. However, when she ran off upon being splattered with blood before learning the source of her phobia, A dismissed her state of mind as a weakness would not trust his mens' lives to her with Shizune defending her mistress.
He was first seen when he received news of Killer B's capture by Akatsuki. Enraged that his own brother had been lost so soon after Yugito Nii, A called for a meeting of the five Kage to discuss Akatsuki. Because B's captor was Sasuke Uchiha, a former Konoha ninja, A had Team Samui take a letter to the Hokage to inform Konoha that he would personally deal with Sasuke.
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 with 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 voiced his suspicions of the other Kage: that Sunagakure used Akatsuki in order to destroy Konoha; that the Third Tsuchikage employed Akatsuki in the past; that the Fifth Mizukage and the rest of her village is the least trustworthy due to suspected ties with Akatsuki. He 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 Shimura, used Akatsuki to dispose of the Third Hokage and the Fourth Kazekage.
When the idea of a Shinobi Alliance was raised, Danzō was nominated to lead it. A was outraged, but before he could raise much of an objection Zetsu appeared and revealed that Sasuke was nearby. A immediately grabbed Zetsu by the neck and demanded information on Sasuke's location, and later broke his neck when he took too long to respond. He then left with C and Darui to track Sasuke down. Upon finding them, A tried to attack Sasuke but he was instead drawn into battle with Sasuke's team. He first snapped Suigetsu's damaged sword and then engaged a transformed Jūgo, A overpowering him after a brief fight. With his team out of the way, A was able to attack Sasuke uninhibited.
Sasuke had difficulty breaking through A's Lightning Release Armour, with his Chidori only managing to cause a minor wound to A. A went on the offensive with his Liger Bomb, but he too had difficulty damaging Sasuke due to the latter's Susanoo. Sasuke tried to hit him with Amaterasu, but A was too fast. 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 to smash through the defence and hit Sasuke. Although his arm was caught ablaze he continued the assault, only to be stopped by the Fifth Kazekage. The Kazekage asked for a chance to speak with Sasuke. Although irritated, A used this as an opportunity to deal with his arm; he cut it off to prevent Amaterasu from spreading to the rest of his body and then had C stop his bleeding.
While A was being healed, Sasuke caused a cave-in to cover his escape. A smashed the falling debris and joined the Kazekage in pursuing him back to the Summit hall. When they arrived they were met by Tobi, who sent Sasuke to safety before telling them about his Eye of the Moon Plan, in the process revealing that B eluded capture. Tobi then requested that B, along with Naruto be handed over to him. A and the other Kage refused, prompting Tobi to declare the start of the Fourth Shinobi World War. A Shinobi Alliance was suggested again, this time with A as the proposed leader. The Kage agreed to this before returning to their respective villages to prepare for war.
Before going back to Kumo, A and his men tracked down B. They found him in the middle of a fight with Kisame Hoshigaki. A and B teamed up to decapitate "Kisame" with a Double Lariat. A angrily scolded B for pretending to be captured on their way back to the village. They were informed that the daimyō had agreed to the Shinobi Alliance's formation when they returned. A then convened a war council to assess the village's military-readiness.
A remained at headquarters with the Hokage and the Tsuchikage while the Alliance's armies mobilised. Shikaku Nara provided a great deal of input on how to organise the army and engage Akatsuki's White Zetsu Army, forcing A to acknowledge the calibre of Konoha's ninja. Despite being the leader of the Alliance, A was uncomfortable not being on the front lines; when news reached headquarters of his father's reincarnation, A wished to go and confront him, but opted to send the Tsuchikage instead after learning that Mū was also amongst the reincarnated.
He had a similar response when the First Division engaged the Gold and Silver Brothers. A explained to the people at headquarters about the brothers and made preparations to deal with them should they begin using their Nine-Tails chakra. He had Mabui send the Kohaku no Jōhei to Darui and called in reinforcements from other divisions to help out the First Division. His plans paid off and the brothers were sealed.
Upon learning that B and Naruto had escaped from confinement, A and Tsunade decided to personally stop them, leaving Shikaku in charge while they were gone. Upon intercepting them, A tried to impress upon them the importance of keeping them out of Akatsuki's grasp. Naruto tried to flee using his Nine-Tails Chakra Mode, but A was able to keep up with him and block his escape. Feeling that he wouldn't be able to sway Naruto, A tried to kill him to prevent his capture. B blocked his attack and informs his brother that he would have to be willing to kill both of them. A claimed to have no problem with this, but B unbelieving, bumped fists with him to remind him of all they had been through together. When A still wouldn't listen to words, B attacked and defeated him with a Lariat, proving his strength. Despite his defeat, A still refused the pleas of B and Tsunade, prompting Tsunade to decide to battle A as well.
B however tried once more to reason with his brother, telling him that the tailed beasts weren't the only thing that made them strong but also the people who cared about them, referring to them as "suns". B told A that Naruto had two of them. A then asked him about it and Naruto told him about his parents, and that despite them dying shortly after he was born, they made him strong. After hearing this, A fully charged his lightning armour and attacked, however, Naruto was able to completely evade the attack. With this as proof of Naruto's power, A allowed Naruto to enter the battlefield stating that the "saviour" might still be alive in the form of him. After returning to headquarters, he was briefed about the White Zetsu Army. As Tsunade diagnosed the situation, A asked her if there were any hints on how to defeat Tobi to which she declared that he might just be the true definition of an immortal.