Kitajima-sensei serves as a compassionate school counselor dedicated to students like Kokoro Anzai, Fūka Hasegawa, Masamune, and Haruka Ureshino during their struggles. She is the future incarnation of Akiko Inoue (Aki), one of the seven children who once visited a magical castle. In her youth as Aki, she endured profound adversity: maternal neglect, relentless ostracization by peers, and an attempted sexual assault by her stepfather after her grandmother's funeral. These traumas culminated in a crisis where she contemplated suicide.

Repeating a school year due to these hardships, she eventually completed her education and pursued counseling. Her training introduced her to Mio Mizumori, the terminally ill sister of Rion Mizumori, whose plight deeply shaped her professional direction. This journey forged Kitajima-sensei’s redemptive arc, transforming her past suffering into profound empathy for troubled youth.

In her counseling role, she steers Kokoro through bullying and school reintegration. Her bond with the castle’s legacy remains implicit as she fulfills a promise Kokoro made there, embodying hope and continuity. Her character personifies overcoming personal darkness to guide others through theirs.