Jo-o rules as queen of the fairy world, dispatching five fairy representatives from distinct clans to the human world. Their mission is to heal afflicted human hearts and gather "attachments"—energy crystallized from powerful human emotions. While she presents this mission as vital for rebuilding her kingdom, her true intentions remain concealed.

She possesses a short stature, fair skin, vibrant pink hair secured by rose-shaped accessories, and striking red eyes. Her attire consistently features a frilly white-and-pink Lolita-style dress, paired with white socks, pink shoes, and a matching bonnet.

Her personality is defined by strictness and unwavering dedication to her royal duties. She enforces the Ten Laws of Fairies upon her emissaries, forbidding romance, wrath, envy, revealing their true identities, and other transgressions. Violations carry the potential penalty of demotion to human status, though the precise threshold for this consequence is undefined. Notably, Jo-o deliberately withholds crucial mission details from the fairies, including exact methods for gathering attachments and the ultimate purpose of the collected energy.

Her real name is Procyon. She shares a significant, undisclosed connection with the series' antagonist, Sirius Tenrо̄in—a fallen fairy driven by hatred for both fairy and human realms to seek her destruction. The exact nature of their conflict and relationship remains hidden.

Within the narrative, her central role involves orchestrating the fairies' missions while meticulously guarding the secrecy of her objectives. The purified attachments gathered by the fairies are sent directly to her, yet their final use or destination is never clarified. This ambiguity extends to her broader plans for the fairy kingdom and the motivations driving her manipulation of the main characters.