Kurama

Kurama, more commonly known as the Nine-Tails, is one of the nine tailed beasts. Centuries of being regarded as a mindless monster and sought after as a tool for war caused Kurama to hate humans. After being sealed into Naruto Uzumaki, Kurama attempts to maintain its negative opinions about the world, but with Naruto's insistence on treating it with respect, the fox overturns its hatred and willingly strives to use its power for the world's salvation. Kurama and the tailed beasts first came into being in the waning days of Hagoromo Ōtsutsuki, who used his Creation of All Things Technique to divide the Ten-Tails' chakra into nine separate bodies and giving each a name. Some time after being created, the Sage explained to the young tailed beasts that a link existed between them despite their separation. He also foretold of a day when they would be brought together again - though not as they were - and that at that time someone would emerge to show them what true power is. After Hagoromo's death, the tailed beasts drifted apart, apparently due to Kurama's belief that their number of tails was an indication of their strength.

Over the centuries, Kurama has gained a reputation as an age-old natural disaster, appearing suddenly out of nowhere to attack areas that have been breeding grounds for the darkest aspects of human nature. At one point during the time of the formation of the shinobi villages, the Gold and Silver Brothers of Kumogakure were assigned to capture Kurama, but were both swallowed whole by the fox. However, the two brothers managed to survive and gain some of its power by eating the flesh of its stomach for two weeks, forcing Kurama to regurgitate them. After that event, Madara Uchiha defected from Konoha and used his Sharingan to control and use Kurama to help him fight against Hashirama Senju, the First Hokage, in order to exact his revenge. During their battle, Madara combined his Susanoo with Kurama, increasing the latter's offensive and defensive capabilities. However, Hashirama was able to remove Kurama from Susanoo and released the tailed beast from Madara's control, subduing it in the process. After his victory over Madara, Hashirama deemed Kurama too dangerous to be allowed to walk free and Mito Uzumaki sealed the fox within herself, becoming its first jinchūriki. Over the period of time which included the first two Shinobi World Wars, Mito kept Kurama at bay except for one occasion when the seal had weakened as she was going through childbirth. Toward the end of her life, Mito passed on this status and responsibility to another member of her clan, Kushina Uzumaki, who later became the wife of Minato Namikaze, the Fourth Hokage. Although Kushina was terrified with the responsibility of containing Kurama, Mito assured her successor that the fox's hatred was powerless against her love. Twelve years before the start of the series, after the end of the Third Shinobi World War, the Third Hokage and his wife made preparations to ensure that Kurama would remain sealed within Kushina as she gave birth to Naruto. However, despite keeping her childbirth a secret, a masked man discovered Kushina's location, killing her escorts and managing to break the seal, seizing control of Kurama. Since Kushina survived the extraction, the masked man tried to have Kurama kill her before Minato got her and their son to safety. Soon afterwards, the masked man summoned Kurama into Konoha and ordered it to destroy the village. While Kurama was rampaging in the village and decimating the shinobi forces that tried to repel it, Minato managed to place a Contract Seal on the masked man during their fight to free the fox from the masked man's control. Despite that, Kurama still harboured a deep hatred for Konoha for sealing it away for decades and resolved to destroy the village without orders from the masked man. Before Kurama could annihilate Konoha, Minato summoned Gamabunta on top of the fox, and quickly teleporting it to Kushina and Naruto's location, while letting its Tailed Beast Ball detonate away from the village.

Soon afterwards, Kushina used her Adamantine Sealing Chains to subdue Kurama, planning to seal it back inside her before she dies. However, Minato, knowing that Kurama would revive without a host, and how great a threat the masked man is, came up with a plan to give Naruto the means to combat the masked man in the future when he decides to attack again. Since Kurama's chakra was too immense to be sealed within an infant like Naruto, Minato first used the Dead Demon Consuming Seal to separate and seal its Yin half within himself and then prepared the Eight Trigrams Seal to imprison the Yang half within Naruto. With the chain loosening from the fox's reduced size and Kushina weakened, it attempted to stop the process by killing Naruto, but both of the parents sacrificed themselves to protect their newborn child and completed the sealing. Later, upon awakening within Naruto's subconscious and learning the situation behind Minato's intention, Yang-Kurama, though frustrated of being sealed again, decided to wait for the time to come when it would influence Naruto as much as it can to use its power to break the seal. Throughout the years, Kurama weakened the seal through the cracks of its formation by constantly leaking out small portions of its chakra, which had positive side-effects on Naruto such as amplifying his naturally large chakra reserves and healing ability, being able to heal from minor wounds within seconds to major injuries within a day. In the anime, it was revealed that Kurama had left behind large amounts of its chakra during the attack. Kazuma collected and sealed the chakra within his own son, Sora, hoping to make use of its power for his own agenda. Kurama is a cynical and shrewd individual, along with a somewhat twisted sense of humour. It uses "washi" when referring to itself, which is generally used by older men. Kurama expresses great pride in its power, believing itself to be the strongest of the tailed beasts due to its belief that their strength is determined by their number of tails, which earned Kurama nothing but disapproval from its brethren, especially Shukaku. Conversely, Kurama openly acknowledged the fact that it alone doesn't stand a chance against the Ten-Tails, and from its past experience with Madara, knew full well he is not an opponent to be underestimated, even though he was seemingly pushed into a corner at the time. However, it does easily get annoyed when Naruto uses a power other than its own, claiming its jinchūriki needs no other power than its own. It is also shown that Kurama deeply cares about Hagoromo Ōtsutsuki, viewing him with great respect and even shed tears after the Sage had imparted his final words to them. Long years of receiving humanity's negative treatment caused Kurama to develop intense hostility and distrust against them, even going as far as proclaiming itself to be the living embodiment of hatred. Ever since its sealing within Naruto, Kurama plotted to use the young shinobi's dependence on its power to gain control over him and break free from the seal, before it was bested in combat and stripped of most of its chakra. However, Kurama's attitude towards Naruto soon began to change during the Fourth Shinobi World War, when the young shinobi told the fox that he hoped to resolve its hatred someday. Despite Kurama reproaching him for making such a claim, the fox nevertheless had developed a level of respect for Naruto and his determination. It even noted that Naruto was different from the humans it had previously encountered, eventually allowing its jinchūriki to utilise the Nine-Tails Chakra Mode without consequence. Later, as Naruto told Son Gokū of his desire to save the tailed beasts and become friends with Kurama, the fox having witnessed all of the challenges and endeavours Naruto had in his life silently told the young shinobi that if he truly intended to help them, he would have to prove it through his actions. When Naruto successfully freed Son Gokū from Obito's control, Kurama finally became convinced of Naruto's word and offered to meld its chakra with his as a coalition, to which Naruto then removed the seal that restrained it and happily acknowledged the fox as his team-mate and a member of Konoha.