In the anime and light novel series The Ogre's Bride, Ao is one half of a pair of small, beast-like creatures known collectively as Kooni. Created from the spiritual power of the male protagonist, Kiryuin Reiya, Ao and its counterpart, Sou, serve as his familiars and attendants. Ao is distinguished from its white-haired companion by its black hair. Despite their diminutive and cute appearance, which has made them quite popular, these beings possess considerable combat ability, being highly skilled and powerful enough to force a high-ranking fox spirit like Kogetsu Yota to retreat. As creations of Reiya, Ao is deeply loyal to him and, by extension, to Yuzu, the human girl Reiya claims as his bride. Their primary role in the story is to provide support and protection for the main couple, often using their surprising strength in situations of conflict. While Ao does not undergo significant personal development as a primary character would, its presence as one of Reiya’s creations underscores his immense spiritual power and his role as the next head of the Kiryuin clan, the highest-ranking ayakashi. In an academic or school setting, Ao and Sou are noted to have become something like idols due to their adorable appearance.