Aishia is a high-class spirit bound by contract to Rio, the narrative's central protagonist. Their profound spiritual pact grants Rio access to advanced spirit arts and establishes her as his constant companion. Through their telepathic link, Aishia anticipates Rio's movements in combat, functioning as his moveset clone and enabling them to fight in perfect synchronization. Her capabilities include disrupting magic from divine weapons using anti-magic spirit arts, a crucial asset against adversaries like Lucius Orgueil. As an upper-tier spirit, she represents a rare and powerful entity within the story's spiritual hierarchy. Aishia remains a stabilizing presence throughout Rio's journey, accompanying him across both seasons of the adaptation.