Akiko Inoue, known as Aki, arrives from 1991 as a third-year Yukishina Junior High student. Her absence stems from severe trauma: abuse by her stepfather and the loss of her boyfriend, forcing her refuge away from school. After the abuse, she lived with her grandmother, reflecting a fractured family dynamic that deepened her isolation.

Within the castle, Aki emerges as a natural leader yet deflects personal inquiries about her painful past, revealing guardedness and unresolved struggles. Her defiance peaks on March 29th when she breaks the strict 5:00 PM curfew. This rebellion results in her being "eaten" by the wolf, endangering the entire group and exposing her lingering despair.

Her fate pivots when Kokoro finds the hidden wish key and wishes for Aki's forgiveness, reversing the violation's consequences. This act saves Aki and the group, underscoring their redemptive bond.

Post-castle, Aki transforms profoundly: she adopts the surname Kitajima and becomes a school counselor. In this role, she supports Kokoro, Fūka, Masamune, and Ureshino across timelines, channeling her pain into empathy for others facing similar struggles. During counseling training, she meets Mio, the Wolf Queen, unveiling another thread in the castle's intertwined destinies.