OVA
Description
Eri Ninamori is a twelve-year-old sixth-grade student and a classmate of Naota Nandaba, serving as the president of their class. She is the daughter of the mayor of Mabase and is introduced as a well-regarded figure at school, though her composed exterior masks considerable personal turmoil. Physically, Ninamori is described as tall for her age, with dark blue-green eyes and purple hair. She initially wears her hair long and straight, but it is cut to chin-length during the series and later styled in braids.

At the core of Ninamori's personality is a deep-seated desire to appear mature and composed, a trait she shares with Naota. She projects an image of a proper, and sometimes slightly stuck-up, young woman who has everything under control. This facade is maintained through meticulous effort; she is so concerned with her image that she wears contact lenses at school to conceal the fact that she needs corrective glasses, viewing her eyewear as a representation of her true self that she rarely shows others. Behind this controlled surface, however, she often loses her composure when angry or excited, revealing the emotional child she truly is. Despite her status as a rule-following class president, she is not above breaking rules to achieve her personal goals, demonstrating a pragmatic and calculating side that is surprisingly devious for her age.

Ninamori's primary motivation throughout the story is rooted in her family life. Her father, the mayor, is embroiled in a public sex scandal involving his secretary, which has led to a separation from Ninamori's mother. This situation troubles her deeply, though she initially refuses to admit to the pain it causes, hiding her frustration behind a mask of indifference. Her central motivation is a desperate wish for her parents to stay together. To this end, she rigs the class vote for the upcoming school play, Puss in Boots, so that she can secure the lead role of the Marquis de Carabas and have Naota cast opposite her as the cat. Her plan is that her parents will attend the play together and, seeing her perform, will reconcile.

Her role in the story is most prominent in the third episode, which focuses almost entirely on her perspective. She serves as a direct parallel to Naota, as both are children who act mature to cope with uncomfortable realities, but they have arrived at this behavior through different circumstances. While Naota's maturity is born from a general disdain for childishness, Ninamori's is a specific response to the hypocritical adult world of her parents' failed marriage. This misunderstanding creates a rift in their potential romance, but she still values their connection and gains a better understanding of her own struggles through him. Naota treats her with a distinct respect, sympathizing with her family issues in a way he does not offer to the other female characters.

Key relationships define her actions. Her interactions with Naota are charged with a subtle crush, indicated by her jealousy towards Mamimi and her willingness to show him her true self, including letting him see her wearing her glasses. She confides in him alone in his bedroom about rigging the election, seeking his understanding by explaining that his character's journey of transcending a mask mirrors her own view of finding happiness. Her relationship with her parents is the source of her emotional conflict, and her dynamic with her father's secretary is tense but civil, marked by passive-aggressive comments from Ninamori, who ultimately, according to some interpretations, may have been the one to tip off the press about the affair to get rid of the woman. At school, she is close friends with her male classmates, Masashi and Gaku, who affectionately call her Ninamo, and she even works a part-time delivery job with them.

Throughout the series, Ninamori undergoes a clear development towards genuine emotional maturity. Her arc culminates in the final episode, where, during gym practice, she tells her friends that she finally had an honest conversation with her parents and let them see her cry, admitting she is still just a child. This moment is symbolized by her performing an impressive high jump, which represents her achieving a form of real maturity that Naota has not yet reached, as she has accepted her vulnerabilities rather than hiding them.

Ninamori also possesses notable abilities connected to the series' core concept of N.O., or Nerves of Ocularity. When Naota accidentally headbutts her during a Vespa accident, his opening N.O. channel briefly transfers to her. As a result, when the Medical Mechanica factory siren sounds, a robotic creature partially emerges from a wound on her head. While the robot is stuck inside her, it gains complete control over her, turning her eyes red and granting her superhuman leg strength and combat abilities, allowing her to kick Naota and the robot Canti with rapid precision and even fend off blows from Haruko's guitar. This manifestation is a key plot point in the third episode, where the robot she produces is bulbous and flower-like, contrasting with the more angular robots that emerge from Naota. After the robot is defeated, she returns to normal, her brief experience with N.O. serving as a physical manifestation of the emotional chaos breaking through her controlled exterior.