Princess Qoona is the younger sister of Distol, the prince of the kingdom of Asteria, and one of the central figures of the anime Slutty-Princess Diaries. Eight years after the mysterious death of her mother, Qoona is chosen as the Holy Maiden, a sacred role that requires her to sacrifice her own life, together with her virginity, to give power to the seal that binds the demon king. Although being chosen as the Holy Maiden is normally regarded as an honor, her brother does not want to lose another person he loves, and her fate becomes the catalyst for the events of the story.

The bond between Qoona and Distol is her defining relationship. He is described as holding her in deep affection, and his refusal to accept her sacrifice leads him to accept a witch's offer of great power, which sets him on a path of revenge. Qoona's characterization centers on innocence rather than personal agency; she is presented as a young princess whose destiny is decided by the ritual role imposed on her and by her brother's choices. Her own motivations are not the focus of the narrative, and she is portrayed primarily as someone acted upon by the sacred duty assigned to her and by the schemes of those around her.

Within the story, Qoona is one of the princesses who fall victim to the campaign of corruption and domination that Distol carries out against the nobility. Along with the other princesses, she is subjected to submission training, forced pleasure, control, and humiliation, and she loses her innocence over the course of the series. By the conclusion, she shares the fate of the other princesses, who are transformed into total submissives with no escape and sealed in an ending of absolute domination.

Qoona's notable ability is tied to her sacred office. As the Holy Maiden, her life and virginity function as the power that sustains the seal binding the demon king, making her a ritual linchpin of the kingdom's magical protection rather than a combatant.