OVA
Description
Aki Nijou serves as the school nurse at Tenbi Academy and also acts as the staff advisor for the Student Council Security Committee, known as Maken-Ki. Prior to her current role, she was a student at Tenbi and a member of the original Maken-Ki, alongside her former classmates Minori Rokujou, Tomika Amato, Gen Tagayashi, and Akaya Kodai. Even from elementary school, Aki possessed a notably large bust, and her mother assured her that her physique would attract a good husband, inspiring Aki to aspire to become a wonderful wife.

In her role at the academy, Aki is a compassionate and gentle figure who is kind to both students and staff. She takes her duties seriously, dedicating significant time to helping with student training and monitoring their well-being. Her professional demeanor and striking figure, which includes being the largest-busted character in the series, have made her the object of many male students' fantasies. Despite her mature and professional appearance, a running gag involves her being a clothing klutz, as she constantly and unintentionally reveals parts of her body, most commonly her underwear. This naive immodesty is a persistent personality quirk.

One of the central aspects of Aki's character is the contrast between her outward maturity and her personal insecurities. Despite her veteran figure and attractive physique, she has never been in a relationship and is a confirmed virgin, a fact she is very self-conscious about. When her virginity is revealed to others, she is mortified and begs them to keep it a secret. Her mother frequently tries to arrange marriages for her, which Aki constantly refuses as she prefers to sort the matter out for herself. To avoid these arranged meetings, she once lied that she had a boyfriend and sent her mother a photo of herself with the protagonist, Takeru Oyama, which instead led to her mother sending the two of them on a trip together, bound by elemental handcuffs.

Throughout the story, Aki serves as a mentor to Takeru Oyama, helping to train him to properly unleash his Maken during a summer training camp. Her relationship with Takeru evolves from a teacher-student dynamic into something deeper. During the forced trip to the island, she experiences his kindness and begins to see him as a romantic interest. After hearing his many compliments, including his statement that she would be a good bride and that he would want to marry her, her self-esteem receives a lasting boost. She later identifies Takeru as her first love. Aki also holds special feelings for her former classmate Akaya Kodai, and she shares a close, long-standing friendship with Minori Rokujou, who often teased her about her body during their school days.

Aki possesses notable abilities that complement her role as a nurse. Her Maken is named Valhelm, which takes the form of a small eye-shaped pendant necklace she wears. Valhelm is a debugging type of Maken, allowing her to medically examine people and see exactly what is wrong with them. It focuses on damage in a person's body and shows it as black spots, with greater damage causing darker areas. Beyond this diagnostic power, Aki is also capable of casting various Element spells. She can use these techniques for healing, as well as for combat purposes such as midair levitation and casting sealing spells. She can also use a spell to erase short-term memories, which she does when Takeru accidentally catches a glimpse of her underwear.
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