Daiya, whose full name is Dia Amafū, is a young girl noticeably younger than the main characters Yuzuka and Chiya. She consistently displays kindness, politeness, and consideration in her interactions, notably influencing others—particularly the typically emotionless Chiya.

Her initial acquaintance with Yuzuka develops into friendship. She subsequently befriends Chiya, who finds her adorable and cute, and later meets and befriends another magical girl, Mafuyu Shinoki, at a cafe.

Despite not being a magical girl herself, Daiya possesses a unique faint sensory ability to perceive supernatural entities invisible and inaudible to ordinary humans. She can see and physically touch the magical creatures Miton and Pochi, though she cannot hear them speak, and her ability extends to seeing ghosts.

This character originates exclusively within the anime adaptation and does not appear in the original manga source material. Her established traits and relationships remain consistent across her appearances.