Aya manifests as two distinct individuals within the narrative. The first inhabits a village of people with erased memories, all potential sacrifices for the yōma. She bears a prominent scar on her left cheek, later revealed as the result of a suicide attempt by drowning after profound personal tragedy, a memory suppressed by the spider yōma priest. This Aya offers shelter and kindness to Hikage, forming a connection. Her death occurs when she drowns in a river after regaining her traumatic memories following the priest's demise, an event triggering mass suicide among the villagers.

The second Aya, encountered later, is a kunoichi fleeing persecution from the Kōga clan who falsely accuse her of assassinating their leader. She meets Hikage on a beach and travels with him. This Aya also possesses a facial scar, bloodied by the demon lord Majuumi no Miko during an attack, giving her an appearance reminiscent of the first Aya. She develops a strong emotional attachment to Hikage, pleading with him to abandon his vengeance against Marou and expressing a desire to remain with him. Her limited combat abilities lead to situations requiring rescue, such as capture by the tree yōma Yōki. Hikage ultimately leaves her behind as he proceeds to his final confrontation.

Both characters share narrative roles as Hikage's romantic interests and victims of the yōma curse. Their similar scarring and names establish thematic parallels regarding tragedy and sacrifice.