Ayumi Azuchi serves as a teacher at Graviton High School, where she is responsible for the class that includes the main characters A-ko, B-ko, and C-ko. Her daily duties involve managing classroom dynamics, which primarily means preventing the frequent and violent conflicts between A-ko and B-ko while also attempting to educate the easily distracted C-ko. She is an adult woman with gray eyes and blue hair that falls to her shoulders.

Haunted by the death of her parents, Ayumi carries a deep-seated fear that she will never experience romantic love or marriage, a sense of underlying loneliness that significantly propels her decisions throughout the series. This personal struggle is a central aspect of her character, influencing her actions and desires beyond her professional responsibilities. In addition to her teaching career, Ayumi is an active member of the Volunteer Defense Force, an organization that mobilizes to protect Graviton City during emergencies. For these missions, she adopts a distinctive and revealing superhero costume, a remnant from the franchise's initial adult-oriented development, and utilizes a gravity-defying cycle for transportation. Her personal interests include literature, watching fireworks displays, and swimming.

Ayumi's role in the story becomes particularly prominent in Project A-ko 4: Final. Facing ongoing romantic disappointment, she enters an arranged marriage with a character named Kei, an engagement orchestrated by Hikaru Daitokuji. This wedding becomes a central plot point, provoking intense reactions from both A-ko and B-ko, who are infatuated with Kei. Concurrently, Ayumi exhibits mysterious behavior, wearing a heart-shaped crystal pendant marked with a hexagram and chanting private prayers. This pendant is later revealed to be identical to an artifact discovered in ancient Babylonian ruins, one linked to apocalyptic prophecies concerning an alien princess. The wedding ceremony, held in the high school gymnasium, descends into chaos as it is simultaneously disrupted by A-ko and B-ko's violent interference, the arrival of the Alpha Cygnan alien fleet intent on retrieving their princess, and the intervention of the Earth Defense Force. Ayumi, along with Kei and C-ko, is caught in the middle of this large-scale conflict. Her personal storyline culminates in profound frustration when she smashes her pendant, disillusioned by its failure to grant her the extraordinary life or significance she had anticipated.