Hagoromo Otsutsuki, most widely known as the Sage of Six Paths, is a legendary figure in the lore of his world, regarded as the founder of Ninshu and the progenitor of what would become the ninja world. He was born as the elder son of Princess Kaguya Otsutsuki and had a younger twin brother named Hamura, making them the first humans to be born with chakra. Hagoromo inherited a massive and powerful chakra from his mother, which eventually led to conflict. After Kaguya, corrupted by her power, merged with the Divine Tree to become the Ten-Tails and began a rampage, Hagoromo and his brother fought against her. They succeeded in defeating the beast, and Hagoromo sealed the Ten-Tails within his own body, becoming history's first jinchuriki.

Following this monumental battle, Hagoromo dedicated his long life to spreading peace and spiritual enlightenment. He traveled across the land, disseminating the principles of chakra and teaching a creed known as Ninshu, which was intended to connect people's spiritual energy and foster mutual understanding, rather than conflict. The practice of Ninshu would later be corrupted into the combat-oriented skills known as ninjutsu. His relentless efforts and immense power earned him the titles of the Savior of this World and even a god among men.

In his later years, Hagoromo fathered two sons, Indra and Asura, who were born with his chakra and inherited his philosophies in vastly different ways. Indra was a prodigy with innate, formidable power and a solitary nature, while Asura initially showed little talent but achieved strength through hard work, cooperation with others, and the bonds he formed. As Hagoromo neared death, he chose Asura as his successor, believing that Asura's path of love and cooperation was the true key to peace that he had been seeking. This decision, however, sowed deep-seated jealousy and bitterness in Indra, leading to a fatal quarrel between the brothers that would continue for centuries through the reincarnation cycles of their descendants. Aware of his folly and the conflict he inadvertently created, Hagoromo left behind a tablet detailing his history, hoping to guide his descendants away from repeating the same mistakes. Unbeknownst to him, the entity Black Zetsu later altered the tablet's contents for its own schemes.

Hagoromo's personality is consistently portrayed as wise, benevolent, and deeply compassionate. He possessed a strong sense of justice and a desire to end the violence and oppression that plagued the early world. Despite his god-like status, he was known to be humble and modest, openly acknowledging his own failures as a father regarding his sons. He is also shown to be exceptionally patient and calm, even in the face of passionate outbursts from those he mentors. He held a great love for all living things, not least of which were the tailed beasts, which he treated as individual children, giving each a name and encouraging them to find their own way in the world.

His role extends beyond ancient history into the present day of the story. Even long after his death, his powerful chakra and consciousness persisted, allowing him to observe the world of the living. During the climactic battle of the Fourth Great Ninja War, he appeared in a spiritual plane to the reincarnations of his sons, Naruto Uzumaki and Sasuke Uchiha. He explained the long history of his mother, his sons, and the cycle of hatred, before bestowing upon them half of his power each the Six Paths Yang power and Six Paths Yin power to provide them with the means to finally defeat the revived Kaguya and break the cycle of conflict.

Hagoromo's key relationships are central to the entire history of his world. His relationship with his mother, Kaguya, is that of a son who ultimately had to oppose and seal away his own parent to save humanity. He shares a deep bond of trust and cooperation with his brother, Hamura, with whom he fought and sealed the Ten-Tails. Following their victory, Hamura led a branch of the clan to the moon to stand guard over the sealed Gedo Statue, while Hagoromo remained on Earth. However, his most defining and consequential relationships are with his sons, Indra and Asura. Hagoromo's decision to choose Asura as his successor created an irreparable rift, turning Indra from a prodigal son into a bitter rival. This fraternal conflict, and Hagoromo's resulting guilt and regret, form the foundational trauma that shapes the entire shinobi world and the rivalry between the Senju and Uchiha clans. His final relationship in the story is with Naruto and Sasuke, the latest reincarnations of Asura and Indra, to whom he entrusts the future he could not achieve himself.

As a figure whose power is described as god-like, Hagoromo possessed numerous extraordinary abilities. As the original jinchuriki of the Ten-Tails, he commanded its unimaginable chakra. His dojutsu, or eye techniques, included the Rinnegan, which gave him mastery over all six nature transformations and the abilities of the Six Paths Technique. He was also a master of Six Paths Senjutsu, a powerful form of sage art that allowed him to fly and manifest Truth-Seeking Balls, orbs composed of all five basic nature transformations and Yin-Yang Release that could nullify all ninjutsu. With his god-like Yin-Yang Release and the Creation of All Things ability, Hagoromo was able to take the chakra of the Ten-Tails within him and divide it into nine separate bodies, thus creating the tailed beasts. He was also a master of powerful sealing techniques, capable of using a colossal Chibaku Tensei to create the moon as a prison for the Ten-Tails' empty shell after he had extracted its chakra.