Kaguya Ōtsutsuki

Princess was the first human to use chakra after consuming the fruit of the Shinju.

Background
Long ago before the founding of the hidden villages, during an era of endless wars between mankind, Kaguya — who came from a far away land — decided that it was necessary for someone to attain god-like powers in order to stop the constant conflicts. For this reason, she consumed the forbidden fruit of the Shinju, gaining the ability to manipulate powerful chakra and allowing her to single-handedly put an end to all the wars that plagued the lands. Some time after this Kaguya gave birth to two sons, one of which was named Hagoromo. They both inherited this powerful chakra and were able to manipulate it. However, the Shinju's desire to reclaim its stolen power caused the tree to assume a monstrous form, which became known as the Ten-Tails.

The furious Ten-Tails rampaged throughout the lands until Kaguya's sons defeated and sealed the beast, making Hagoromo the first jinchūriki. Hagoromo would later teach humanity the concepts of chakra, becoming revered as the Sage of the Six Paths, in an attempt to make people use chakra to connect to each other, rather than using it as a weapon as Kaguya had done.

Personality
While Kaguya desired to create peace like her sons and grandsons, Kaguya opted for a more forceful method, using her great power to make people submit to her will. As Hagoromo noted, people in time began to fear her as a demon for her methods.

Appearance
A woman in possession of very delicate facial features, Kaguya also had long, sweeping light coloured hair that touched the ground. Most noticeably were two horn like protrusions which stuck out from her head — appendages inherited by both her sons. Kaguya possessed the Byakugan, and also had a third eye on the centre of her forehead that's eyelids parted vertically. Her eyebrows were cut very short — a symbol of nobility, and she wore a dark shade of lipstick on her lips and a dark shade of nail polish on her long fingernails. She wore the transitional high-collared hime-kimono which was adored with intricate lines and tomoe running down the centre and edges of the gown.

Abilities
After consuming the fruit of the Shinju, Kaguya achieved such unrivalled power that she was able to pacify the war-torn world all by herself, leading the people to worship her in fear. Hagoromo, being a legendary figure himself, praised his mother's might as superior to all others, including his own. In one portrayal of her, Kaguya was shown manipulating lightning, causing a thunder storm.

Dōjutsu
Kaguya is one of the rare individuals that possessed a dual dōjutsu combination of the Byakugan in both eyes, and the Sharingan in a third eye on her forehead. Using both, she was able to quell the fighting in her era and even was said to use Infinite Tsukuyomi.

Legacy
Despite Kaguya's meaningful attempts to bring forth peace, her methods would only inspire the people of Hagoromo's era to weaponise chakra for wars instead of using it for peace, which would include the tailed beasts being seen as nothing more than masses of powerful chakra to exploit and control.

Trivia

 * Her name and title are likely references to Princess Kaguya, the main character from, which is said to be one of the oldest Japanese legends in written record. According to the legend, Princess Kaguya wears a when she returns home to her kingdom. The name  roughly means "big bamboo tree" and is derived from an obscure passage in the second volume of the Kojiki about the genealogies of Emperor Suinin, eleventh emperor of Japan, which states that he had a consort named , the daughter of a king named ; tradition holds that these individuals served as the basis for Princess Kaguya and the old bamboo cutter in the aforementioned tale.
 * Her horn-like appendages may symbolise rabbit ears, representing her connection to the moon by evoking the moon rabbit; pop culture depictions of Princess Kaguya and the moon-folk often incorporate features like rabbit ears for this reason. This also fits with her being known as the.
 * The concept of a woman eating forbidden fruit may be based on the Bible's Book of Genesis, in which Eve ate the fruit from the tree of knowledge, which led to the original sin of mankind.
 * Her Sharingan greatly resembles the Shinju's unique eye.
 * Despite the Byakugan she had, it's unknown if the Hyūga clan is directly related to her.