Miss Ayumi is a teacher at Graviton High School who has A-ko, B-ko, and C-ko in her class at the same time. This means that she has the task of trying to get C-ko to learn while preventing A-ko and B-ko from murdering each other.
Later, we learn that Miss Ayumi nurses a secret gloominess in her soul. Her parents are both dead, and she worries that she will never fall in love. This leads to her fateful decision to accept an arranged marriage with Kei.
Miss Ayumi is also a member of the Volunteer Defense Force, a loose-knit organization of do-gooders who defend the city when the authorities fail. When A-ko and B-ko's brawl sparks a citywide alert in "Cinderella Rhapsody," she immediately dons an outlandish superhero costume and rides a gravity-defying cycle into action. Her skimpy outfit was a holdover from the time when Project A-ko was going to be an adult series.
Miss Ayumi is modeled after the lead character of the eponymous TV series Creamy Mami, one of several magical girl TV shows that came out during the 80s.
Miss Ayumi's subject appears to be literature. She loves fireworks displays and is an avid swimmer.
(Source: Wikipedia)
