Aya is a popular magician with the performance group IAM, wielding the Incomprehensible Skill of Human beings (ISH). This power enables her to manifest physical illusions, most frequently in the form of large, grotesque monsters that can inflict significant damage.

Her misanthropic behavior and philosophy stem from childhood experiences where she was viewed as a freak due to her abilities. The only person she felt understood by was her mother, until an attempt to use her powers to bring her mother joy instead caused her mother to become frightened of her. This event led Aya to use her powers solely for her own amusement and to frighten others.

She is sent by a man named Hasudou to investigate and assess the ISH potential of another girl, Amane Todoroki. After observing Amane's performance, Aya deems her unremarkable. Aya's own performances with IAM are designed primarily to frighten audiences, aligning with her belief that people cannot understand ISH users and that coexistence is impossible.

Aya confronts Amane on multiple occasions, attacking her during a show with an illusionary monster. This confrontation leads to a situation where Aya's own memories and emotional barriers are overcome, and visions from her past are revealed. These visions detail the rejection and isolation she faced, which shaped her negative worldview. With assistance, she is freed from these emotional barriers.

Freed from her feelings of hatred, Aya changes her ways and decides to join Amane's performance group, Nought. She concludes her story by participating in a collaborative show.