Ei Gyōmei is the Crown Prince of the Kingdom of Ei, a position that places him at the very center of the political and social hierarchy of the Maiden Court. He is described as a man possessing both wisdom and strength, presenting a figure who is handsome, sincere, and carries a strong sense of responsibility. His talents are understood to span both the arts and combat, marking him as a well-rounded and capable leader.

In terms of personality, Gyōmei is defined by his deep affection for Kou Reirin, a young woman known as the "Butterfly of His Highness" for her intelligence and grace. This affection shapes his initial perspective within the story. His feelings for Reirin are contrasted sharply with his disdain for Zhu Getsuei, the series' titular "inept villainess," whom he reportedly despises. This dynamic is critical, as Gyōmei witnesses the pivotal event of the narrative: Zhu Getsuei pushing Kou Reirin from a tower. Unaware that the two have magically swapped bodies, his subsequent actions are driven by the information available to him, leading him to order the expulsion of the person he believes to be Getsuei from the court.

His role in the story is therefore that of a catalyst and an authority figure whose romantic attachments and judgments propel the central conflict. He is the object of affection for the court and his favor dictates much of the social standing of the female apprentices. While he harbors a genuine love for the intelligent and composed Reirin, his hatred for Getsuei sets the stage for the latter’s exile and subsequent journey. Key relationships for Gyōmei include the palace official Shinu, who is responsible for maintaining moral discipline within the inner court, though the nature of their working relationship is not detailed. The search results do not provide information on his background before the story, his personal motivations beyond his love for Reirin, his own character development, or any notable abilities beyond his general talents in wisdom, strength, and the arts.