Mikoto's origins are that of Kirigakure. She is the first-born of a Main Branch Hyūga father, with her mother being an Ōtsutsuki. Two years down the line her younger sister, Aiko, would be born. At the age of seven she had entered the academy, where she would train in the basic ninja arts. She had naturally excelled though, due to the strict teaching and training from her father at a younger age. Mikoto would oftentimes become frustrated while training, and talk back at her father. This would of course, end up in putting her into a time-out most of the time.
By the age of 10, Mikoto had passed her academy exams and became a Genin. But even if it had been very satisfactory for herself, her father was not yet satisfied with her growth. Reaching Genin had in fact caused her training to become even stricter, which was the opposite of what she had hoped for. Even though she had been contempt with being a Genin, her father was not.
After three more years, she was allowed by her father to participate in the Chūnin exams. In all three tests, she had passed very easily. During the exams, a grunt sound nin would offer her the chance to leave her village and join Otogakure. She of course declined the offer, and continued with the exams. Her two team mates had been gravely injured during the exams. But she did not care for them, as she was only brought up in the forms of combat, but had very little raising in the area of morality. After meeting up with her father, he still held a look of disapproval upon her. Apparently it was not enough to satisfy him, as he would mention soon afterwards of more training for the Jōnin exams. Frustrated, Mikoto ran off when she found the chance to. Though after a bit of running, she would accidently run into the same sound nin as before. He was about to depart back to his village, along with the rest of his team. The grunt had even more interest in her, as he had noticed that she was uncaring of her team mates, which he mentioned had only held her back. He once again gave her the offer of joining Otogakure, stating that she would only become stronger than she was. With looks of hope in her eyes, she accepted, wanting to leave behind her unsatisfied father.
Many years later and into the present, Mikoto has become a fiercely loyal sound nin. She likes to mostly be independent, but also knows when to pick her fights, and how to interfere with other fights from the side lines. Down the path of her growth, she had come across a mysterious scroll which had apparently been a summoning contract of sorts. This had allowed her the personal summoning of the Doki. And with her flute-produced Sound Release, she has come to manipulate these demonic beasts, with their full powers in hand. Her desires to become stronger grow each day, and stem unconsciously from her father's will.
Many describe her as cold and sharp-tongued, even to her own comrades. Mikoto looks to fulfill her own needs and desires before others. In missions she keeps her focus on the goal, to the point of disregarding her partners and making them fend for themselves. Though such is the norm of a Sound shinobi.
Mikoto is well-versed in the use of water and lighting release, being able to use them in conjunction to her advantage. Though she is more likely to use water release often, as it is more advantageous to use with her dōjutsu and genjutsu.
Being a Hyūga, Mikoto naturally bears the Byakugan. She also sports the Hyūga's fighting styles of the Gentle Fist. Her current maximum field of vision with her Byakugan active is 10km. Through her self-training, she has come up with a custom taijutsu style known as Nanto Seiken, which involves causing severe external damage and dismemberment of an opponent. This was conceived from her use of the Chakra Scalpel technique.
Cursed Seal of HeavenLocated on the left side of the back of her neck. After attaining favor and loyalty to Otogakure, Mikoto was granted a cursed seal for herself. For most shinobi there was always the one in ten chance of survival. But due to Mikoto being of Senju lineage, her vitality had allowed her to overcome the overwhelmingly obvious outcome of death. She is currently only able to use the first form of it. Upon activation, flame-like patterns begin to cover most of Mikoto's body on the left side and grant her extra chakra reserves. Her physical prowess increases just a bit too.
Upon further training with her Cursed Seal, she would undergo the false-death ceremony and would emerge hours later within the Cursed Seal's true and final transformation. While in this form Mikoto's skin turns a shade of dark grey, a black four-pointed star appears between her eyes and across the bridge of her nose. Her sclerae turn black and lips turn blue. Her nails also grow into claw-like forms. She may also spawn large webbed hand-like wings that can allow her to fly and hover, though she prefers not to form them. While in this form, her strength, speed and endurance are increased. Furthermore, chakra capacity and jutsu are greatly enhanced, with any jutsu performed being of greater strength.
Wanting to delve further into the Sage Arts, Mikoto undertook training with being able to gather Natural Energy herself, instead of having the rely on the Cursed Seal of Heaven to feed her Senjutsu Chakra in exchange for feeding the seal her own.
Developing a Sage Mode based off the aspects of the Doki would prove to be the most extraneous part of her Sage Mode training. More-so due to the abnormal physical appearance it would give her, which in her own opinion had made her look ugly. Though in time her training in being able to gather Natural Energy and balance it as an equal third component with her Physical and Spiritual Energies would eliminate the symptoms of her fading beauty. Instead the perfected form would instead alter her hair's color to turn white and her head growing two flat horn-like protrusions.