Otoha was presumably born and raised in Kumon-mi. While her parents are unknown, it can be assumed that they have a more traditional world view as they want Otoha to follow a more traditional role for a woman instead of pursuing her music career, demand her presence during holidays and have a negative opinion on same sex relationships. They financially support her vocal lessons, but have an iron grip on everything she does, don’t hesitate to take all of her liberties away if she doesn’t follow their rules and control most of her life, giving her next to no freedom.
Assuming that he didn’t betray Rin, User meets her for the first time during Rin’s post-heartbreak excursion in I Died With You and helps her to get Otoha’s attention. He later learned in Fuck Christmas that both have gotten closer and were texting each other constantly.
He himself had no contact with her until Nodoka wanted to transfer into his class on the condition that he convinces Otoha to enroll as well. Reason being that she was also a student at Kumon-mi Academy, but unlike everyone else she wasn’t transferred to Kumon-mi High, because her parents decided to home-school her instead. With her grades declining as a result of her suffocating home life, she’s forced to retire as a musician if nothing changes and Nodoka wants to use User’s ‘teaching methods’ to prevent this. He managed to get through to her and, after her parents agreed, she joined a few days later.
Otoha is perceived as a cool and interesting girl, which makes her popular with almost everyone she meets. She’s easily approachable and friendly during her interactions. She also has a serious personality and is one of the more normal and levelheaded girls in class.
Unlike most of the other girls, she has no tolerance for perversions and gets quickly annoyed by it. When this happens, she makes her displeasure known, something that happens often during her interactions with Nodoka and User. This, combined with her more traditional world view, is a major reason why she sees User’s more personal interactions with his students and her peers open interest in him as kinda creepy and wrong on some level, but the few times she brought this up the others either shut her up or didn’t agree with her.
Otoha never had a romantic interest in anyone and is even more hesitant to start something with a girl, something that’s partly influenced by her parents. As a result, she has no real idea how to show romantic affection after entering a relationship with Rin and treated their relationship more as an advanced form of friendship during the early days. She similarly awkward with discussing her own insecurities or issues, typically talking around them or trying to ignore them entirely.
While Otoha enjoys more freedom due to User giving her good grades, she is still aware of how fragile her freedom is and fears that one wrong step will result in her losing everything she has. This is why she reprimanded User for his actions during one of his visits and still keeps her relationship with Rin a secret. She also has a bit of a temper when it comes to her music, snapping at User for suggesting she change her habits, or getting passive-aggressive with Chika when she offered help with Sana.
She is confirmed to be lactose intolerant.
Otoha's mother was also a musician in her youth and even went on small tours through Japan with her band.