Aki Nijou teaches at Tenbi Academy while also holding the deputy head position within the student council. Her duties involve overseeing student activities, specifically those of the Security Committee. She specializes in barrier magic, employing this ability to create protective shields during combat training and official school matches.

Her responsibilities extend to the academy's summer training camp on Okino Island. During one island incident, a misunderstanding orchestrated by her mother resulted in Aki being transported against her will and stranded alongside Takeru Ooyama. They remained together until discovered by Haruko Amaya and Kodama Himegami.

Aki exhibits visibly flustered behavior in interactions involving Takeru, stemming from past incidents and accidental encounters. She maintains discipline during school activities, though she occasionally finds herself entangled in unconventional circumstances related to student affairs and training exercises.