Ayari Shiki serves as the head of the student council at Ame no Kisaki Catholic School, a position that places her at the center of school authority and social events. She is a cousin to both Mariya Shidou and Shizu Shidou, which creates a complex family dynamic within the school environment. Despite this familial connection, Ayari shares a significant and long-standing rivalry with Mariya, a conflict that defines much of her public persona and interactions within the story.

Ayari is depicted as a diligent and responsible individual who takes her duties as student council president seriously, presenting a composed and capable front to the student body. However, this serious demeanor masks a more personal and deeply held grudge. Her motivation is largely driven by a childhood incident that she has never forgotten or forgiven. In her youth, during a school event, her dress was torn open, exposing her underwear which featured a panda character design. This led to her being humiliatingly nicknamed Panda-Chang by her peers, a moniker that has followed her and caused her lasting embarrassment. She firmly believes that Mariya was responsible for this act, and as a result, holds a bitter resentment towards him.

This rivalry is openly hostile and characterized by petty insults and public antagonism. Ayari frequently refers to Mariya as Flat Chest, to which he retorts by calling her Fat Ass, a nickname that strikes at her own insecurities. The two share a notable physical resemblance and are of similar height, a fact that seems to fuel their competitive dynamic. Their antagonism is so well-known that when they share a stage during a school assembly, the tension between them is palpable, and they trade whispered insults behind forced, polite smiles.

In her role within the story, Ayari acts as a foil to Mariya, representing a rival power structure and a source of personal conflict from his past. She is also involved in the lives of other students, such as offering help and advice to the protagonist, Kanako Miyamae, during preparations for school festivals and academic matters. Despite her rivalry, she is capable of moments of kindness and reflection, as shown when she discusses her agnostic views and the importance of everyday acts of kindness.

The character exhibits notable development, particularly in revealing the hidden layers of her relationship with Mariya. While the ostensible reason for their feud is the Panda-Chang incident, it becomes clear that Mariya may not have been the true culprit, with evidence suggesting that it was actually Shizu who caused the accident. Furthermore, Mariya is shown to harbor a genuine, if reluctant, desire to reconcile with Ayari, demonstrating a softer side towards his relatives that he usually conceals. In one significant instance, despite their public animosity, Mariya rushes to catch Ayari when she nearly falls during a festival event, an act that briefly hints at a possible mending of their relationship. However, the moment is shattered when Ayari overhears him mutter about her weight, causing her to react with fury and reinforcing their cycle of conflict. This suggests that her pride and the deep-seated nature of her childhood humiliation continue to prevent any genuine reconciliation.

Ayari does not possess any supernatural or extraordinary abilities. Her strengths lie in her organizational skills, authority as student council president, and her determined, if somewhat stubborn, personality. She is a normal human character whose influence comes from her social standing and her personal history with the central cast.