Aki Nijou (二条 秋 rōmaji:Nijou Aki) is the school nurse. She is also the staff-advisor of Maken-ki. She was in the maken-ki of the school before it became an all girl's school. She has absurdly buxom breasts, the largest bust of the cast, which perversely attracts all male students's attention and the envy of girls around her. In addition to this, Aki is unexpectedly still a virgin even with her veteran figure.
Aki is rather tall with her blue hair and light brown eyes. She has a slender, curvy figure and giant breasts. She currently has a K cup bust.
Aki's primary and common attire consists of her wearing a large white lab coat which she keeps open, since she is a school nurse of the academy. Under the lab coat she wears pink strapless top which is openly laced down the middle revealing a lot of her cleavage, along with a very short brown skirt. The aforementioned short skirt does have a tendency to ride up on her whenever she stretches or bends over, in which case she is typically seen wearing green panties.
Matching her slightly naive immodesty, Aki typically wears very revealing clothing, with her typical skirt being extremely short, usually riding up whenever she would stretch or bend over revealing her panties, and one of her swimsuits was a simple sling bikini which was thin enough to reveal her nipples. With her buxom bust and voluptuous body among all woman in Tenbi, Aki is obviously become a fantasy subject to all the male figures in the academy.
In a flashback in the 5th episode of season two, it was shown that Aki had already developed large breasts by the time she was 12 in elementary school.
Aki is one of the benevolent, gentle figures and she is very kind with all the students and all the school staff. She is shown to be a very naively immodest person when situations arise. A running gag of this personality quirk of hers is the fact that she is constantly shown revealing some part of her body - most commonly her panties - unintentionally.
Despite her appearance Aki has never had a relationship and is still a virgin, and is in no hurry to change that fact, as seen in season 2 episode 5 OVA where she tried to pass of Takeru as her boyfriend to avoid her mother setting her up. She does want a relationship but would like to sort the matter for herself. When Minori reveals her virginity to Takeru and Kengo, she is mortified, and begs the boys to keep it to themselves.
Valhelm - Aki's maken is a debugger type, allowing her to medically examine people and see exactly what's wrong with them. It focuses on the damage in people's bodies and shows it as black spots, with greater damage causing darker areas.
- Aki's bust is the largest of all female characters.
- She seems to be developing feelings for Takeru according to chapter 63.
- Along with Minori, Aki is one of Takeru's mentor who trained him to unleash his Maken within during the student training camp.