Devi Ōtsutsuki

Princess was the daughter of Hamura Ōtsutsuki's middle son and a direct ancestor of the Hyūga clan's main family.

Background
Devi was born to Hamura's second son, inheriting a rather powerful Byakugan, which would later coin her as the first.

Devi fought Saimei alongside her cousins, Indra and Asura, wielding the fūinjutsu used to seal her aunt away.

Personality
While growing up, Devi was a rather shy and pessimistic child, easily intimidated even by her own family members, who she claimed were all better and more capable people than she was, particularly her cousins, sons of the Sage of the Six Paths. As such, she grew up a tad stoic. Nonetheless, she admired them greatly, and took an interest to martial arts when she saw Asura training, particularly styles that emphasised in graceful, but quick and effective moves.

After losing her father to her aunt, Devi felt much betrayed by her own family and lost. During this time, Hamura came to her in a dream, telling her to rediscover herself through deep self-analysis, and that she would be instrumental in stopping Saimei from destroying his brother's hard work on Earth. This would later lead her to develop the as a martial art and religiophilosophical doctrine, which also borrowed elements from Ninshū. Despite this, Devi can be somewhat wrathful when those she cares about are threatned or harmed.

Appearance
As a child, Devi wore a simple white kimono with three red magatama on her chest. As an adult, Devi wears a white dress with the same red magatama on her chest, detached sleeves held in place by metal bracelets and a similar object around her collar. She possesses long, black hair with some tied in braids to the back of her head and the featureless white eyes of the Byakugan which seem to faintly glow when activated, an unusual trait for the Byakugan.

Abilities
Born with a rather powerful Byakugan, Devi didn't realise her potential until further incentivation, which she eventually worked on to gain considerable power capable of rivalling even Hagoromo's sons, developing the martial art that would become the trademark of the Hyūga and whose effectiveness made their enemies think twice about engaing them in close-quarters combat.

Byakugan
Devi possesses an especially powerful Byakugan, though exactly which aspects are unknown. The dōjutsu grants her a near 360° vision (with the exception of a small blind spot at the upper thoracic vertebrae), x-ray vision, and the ability to see the chakra pathway system, amongst other abilities.

Taijutsu
As the founder of the Gentle Fist and martial arts adept, alongside her unique Byakugan, it's safe to assume Devi became a widely renowned and feared hand-to-hand combatant during her time, as it was stated her open palms could break stone with ease. She's also seen using a jutsu similar to Hinata's Gentle Step Twin Lion Fists.

Fūinjutsu
Devi also shows some degree of skill with seals, as she was able to seal Saimei (albeit with help from Indra and Asura) in an underground temple that held her stuck in time from approximately a millenium. She also developed a percursor or began developing the cursed seal used by the Hyūga main family to keep the branch family in check.

Legacy
In a similar fashion to her cousins, her chakra lingered on very long after the destruction of her body, and has currently reincarnated in Hinata Hyūga. It is implied she had a crush on Asura as evidenced by their interactions with each other, feelings that would resurface in her reincarnation.

As stated before, Devi is the founder of the Gentle Fist martial art that would continue to be adopted by her descendants as the Hyūga clan, albeit with some possible changes to the original doctrine over the years. She also originally laid the foundations for the Hyūga Main Family's Juinjutsu as a method to keep side families from abusing their dōjutsu.

Trivia

 * "Devi" literally means "Goddess" in Sanskrit, to keep in theme with Hagoromo's sons.