"All chakra… belongs to me. Once again, all chakra shall become one!!!"
- Kaguya to Naruto
Princess Kaguya Ōtsutsuki, rarely going by her title, is the source of all the conflict of the entire manga and anime series Naruto, and by far the biggest threat faced by the protagonists (though she is not the final enemy, since Sasuke Uchiha was fought after her).
She is the first being to ever wield chakra, who became an unfathomably powerful goddess in order to save the world from war, only to become a power-crazed tyrant. She turned herself into the demonic Ten-Tailed Beast, and was sealed away by her sons, but not before she could create Zetsu, who would later orchestrate the entire Ninja History to revive her.
She was voiced by Mami Koyama in the Japanese version, and Cissy Jones in the English version. Kaguya Ōtsutsuki belongs to a kind of human-like beings hailing from other dimensions. Where they came from and how they came to be is never explained, but they are somehow connected to the God-Trees: gigantic trees linked to the life-force of their worlds, said to grow from all the blood spilled in conflicts.
Little is known about her in the manga. She is said to be from "another world". Millennia before the start of the story, during an era of endless wars, when the Earth's God-Tree bore the Chakra Fruit that blooms from it once every thousand year, she ate it to become an immortal goddess of nigh-omnipotence.
She used her power to forcefully pacify the entire world and was worshiped worldwide as the "Rabbit Goddess", though she eventually became a ruthless tyrant feared as the "Demon": trapping thousands of people in a dream-world known as the Infinite Tsukuyomi, and turning them into plant-monsters known as White Zetsus.
It is later revealed that she was worried about the arrival of Momoshiki and Kinshiki Ōtsutsuki, two of her clansmen with powers and ambition rivaling her own, and made an army of Zetsus so as to fight them.
At some point, she birthed two children, Hagormo and Hamura. In the manga, it was never explained who the father was or if she was pregnant with her sons while she ate the fruit. She eventually came to resent her sons for having inherited powers from her at birth, and fused with the God-Tree to become a gigantic, eldritch demon known as the Ten-Tailed Beast. The titan rampaged across the world, until it was defeated by Kaguya's sons and sealed within Hagoromo’s body.
The anime vastly expands Kaguya’s story, especially her rise to power and subsequent downfall. She says herself that she comes from "high in the sky". One night, she came down from the stars in a glowing light, appearing in the world near the place where a meteor had crashed long before, with the God-Tree growing from its point of impact. She was immediately brought before Tenji, emperor of the Land of Ancestors in which she landed, to whom she introduced herself as the protector of the God-Tree, but hypnotized him to make him forget it. Tenji invited her to live in his palace, and had a girl named Aino bound to her service, who became her confident.
Kaguya and Tenji, who shared a longing for peace, eventually became lovers, but their romance was cut short by a conflict with the aggressive nation of the Land of That, falsely claiming part of their territory as their own. Tenji tried to solve the matter diplomatically, and forbade attacks on the denizens of the Land of That, under threat of execution. Suzaku, an official from the Land of That who lusted after Kaguya, sent a battalion to capture her, but she retaliated with her powers, killing many of them. Suzaku used it to ask for Kaguya's head, since she had broken Tenji's decree, and a heartbroken Tenji complied, to avoid war no matter the cost.
Kaguya, weakened by pregnancy, and Aino fled from Tenji's archers, until Aino sacrificed herself to save her mistress. Horrified, Kaguya rushed to the God-Tree and consumed the Chakra Fruit. She immediately used her newfound divine power to entrap everyone in the world into the Infinite Tsukuyomi: an illusionary alternate world under her complete control. She bound thousands of the victims, Tenji and Suzaku included, to the God-Tree, to be transformed into White Zetsus, and released the rest of the population, with no memories of the incident. She then took the throne of the Land of Ancestors and expanded her rule to the entire world, using her divine powers to end all wars.
Kaguya birthed her twin sons and ruled peacefully for many years. Alas, she got slowly corrupted by power and her rule grew increasingly despotic, sacrificing people to bind them to the God-Tree, causing it to drain the world’s energy and put it in grave danger. Hagoromo and Hamura, who had been kept in the dark by their mother, were told the truth by the Toad Sage Gamamaru. They pleaded with her to cease the tributes, but she evasively answered that she would keep going until "the others" (Momoshiki and Kinshiki) were dealt with, and refused to relent.
Gamamaru later taught Hagoromo the Sage Arts, consisting in harnessing and using natural energy. But Kaguya confronted Hamura and learnt of her sons' intention from his mind. She brainwashed Hamura to make him fight Hagoromo to the death, but Hagoromo was able to defeat him and to save him with Gamamaru's help. Enraged by their "betrayal", and determined to take back their powers, Kaguya fused with the God-Tree to transform into the nightmarish Ten-Tailed Beast. Hagoromo and Hamura fought the titan for months, during an apocalyptic battle that wrecked most of the world. They eventually managed to defeat it, saving the recent victims of the God-Tree.
Hagoromo used the god-like powers he gained from being the Ten-Tails's jinchuriki (human host) to split the Ten-Tails' energy into nine Tailed Beasts, and he and Hamura created the moon to seal its husk. Hamura later departed to the moon and started his branch of the Ōtsutsuki clan to watch over it. Hagoromo walked the earth to mend the rampage, and taught the population the art of Ninshu: the use of chakra (life-energy) to perform supernatural feats, in order to create durable harmony through understanding, becoming the mythical figure known as the Sage of the Six Paths.
Unfortunately, unbeknownst to both of them, Kaguya created a shadowy being known as Black Zetsu shortly before being sealed. Black Zetsu remained hidden and waited for an opportunity to revive its "mother".
Hagoromo had two sons: Indra, who wielded incredible power and favoured might, and Asura, who wielded incredible energy and favoured love. While initially considering Indra his heir, Hagoromo came to favour Asura's philosophy of cooperation. Seeing an opportunity, Black Zetsu played on Indra's resentment and turned it into outright hatred, locking both brothers and their descendants into an endless conflict.
He later twisted Hagoromo's teachings and corrupted Ninshu into Ninjutsu, the use of chakra powered feats to fight, restarting the endless wars even worse than before. He wanted to influence one of Indra’s descendants into freeing the Ten-Tails and then Kaguya, enabling her to restart her rule.
In the decades preceding the start of the story, he manipulated Madara Uchiha and his apprentice Tobi, posing as the former's creation and servant, to create Akatsuki and put the plot into motion.
Kaguya Ōtsutsuki is a tall and slender woman with sharp features and aristocratic support, whose white skin, silvery hair, and two spots over her white, pupiless eyes, show her non-human origin. She wears red lipstick and has very long flowing hair, over twice as long as she is tall (thrice in the anime) and wide enough to cover her surroundings. Upon eating the chakra fruit, she grew two brown horns resembling a rabbit's ears, hence her title, long, pointed black nails, and a third, red eye on her forehead, with concentric circles and nine tomoes around the pupil.
Kaguya's entire character, design and speech pattern included, is based on noble women of Ancient Japan. This shows in her long, white gown with gold and purple trimmings, covering her entire body (in fact a kimono worn by princesses), and her eyebrows cut very thin and short.
Kaguya is notable among the villains of the series for being disturbingly devoid of humanity. Even Naruto, the primary protagonist, who could sympathize with most of his foes and differentiate the heroes they once were from the monsters they became, was unable to relate with her. Hagoromo’s ghost notes that she once was well-intentioned but became twisted, most likely due to consuming the Chakra Fruit.
The anime develops her character and confirms that she was a kind soul before getting corrupted. At first, she was highly reserved, somehow disconnected from humans she was alien to: speaking only when she had to and almost never displaying her feelings. She spent her nights looking at the stars, lost in her thoughts. She knew that her destiny was linked to the God-Tree, and feared that her kinsmen would one day come to Earth to take her away.
Although she defended herself when attacked and erased the witnesses' memories of it after that, she only used lethal force when she had no choice and warned her foes beforehand. She deeply desired harmony for the entire world and was very protective of her loved ones. Over time, she grew very close to her servant Aino and her lover Tenji, caring for the world and wanting to make it a place where her children could live safe and happy.
Unfortunately, her growing worry of Momoshiki's ambitions, the betrayal of her lover and children (though the latter was caused by her increasing evil), and her too huge power, gradually twisted her mind. Though she still cares in some way, as she states that she wants to preserve her treasured Earth; and she cried when reminded of her once beloved sons, (though she became furious immediately after and stated to hate them); she has become stern, cruel, remorseless and uncaring. While always distant, Kaguya has become nearly emotionless, keeping a creepy stoic exterior in all situations and conveying her feelings through expressions rather than words.
Kaguya is poised, collected, impassive and cold, but extremely arrogant and conceited. She dismisses her foes as worthless weaklings, and does not even bother to acknowledge those too far beneath her. She is even more self-absorbed than Madara Uchiha himself, which is saying something. Her initial intent to gain divine powers to save humanity from itself gradually worsened into intense paranoia and megalomania, resulting in a God Complex.
She regards herself as the only one fit to rule the world, dismisses humans as unworthy of freedom, wanting to turn them all into monsters slaves to better control them, and cannot stand the idea of anyone else wielding powers. In a way, she makes a chilling representation of both the overbearing mother who refuses to let her children leave the nest, and the tyrannical deity who wants absolute control over every aspect of their creation.
Although she loved her sons, she never deigned to tell them about her goals and motivations, and immediately resorted to violence when they tried to reason with her, instead of listening to their pleas. Worse, she had them fight to the death without caring the slightest about the emotional turmoil it would cause them. However, she greatly trusts Black Zetsu, listening to his advice even when she does not like it; most likely because he is totally loyal...
Kaguya is a no-nonsense woman. In stark contrast with the show-offy Madara, she goes straight for the kill and proves cautious when dealing with foes. She is also very perceptive and pretty smart, immediately noticing her sons' secret. The fourth data book states that she devised Black Zetsu's plan on the spot when she created him.
However, her over-reliance on her powers and obsession with taking all chakra for herself prompt her to make careless mistakes. And like many powerful villains, keeping underestimating the foes who repeatedly proved a challenge, coupled with her paranoia, led to her final defeat. Even when defeated for good, she was thoroughly unable to fathom how it was possible.