"Princess Knight" is a classic anime series based on the manga by Osamu Tezuka, set in a fantastical medieval world. The story revolves around Princess Sapphire, a young noble born with both a male and female heart due to a mischievous act by the angel Tink. In the kingdom, only males can inherit the throne, so Sapphire is raised as a prince to secure her right to rule. Her dual-gender identity becomes a central conflict as she navigates societal expectations, political intrigue, and personal relationships.

Sapphire’s life is complicated by the schemes of Duke Duralumin, who seeks to usurp the throne by exposing her secret. To maintain her disguise, Sapphire adopts the persona of a dashing knight, often switching between her royal and heroic roles. Her courage and determination are tested as she protects her kingdom from external threats and internal betrayals. Alongside her loyal companions, including the fairy Tink and the knight Franz Charming, Sapphire confronts adversaries such as the witch Madame Hell and her minions, who seek to destabilize the kingdom.

The narrative explores themes of identity, gender roles, and justice, as Sapphire struggles to reconcile her true self with the expectations placed upon her. Her journey is marked by moments of triumph and vulnerability, showcasing her resilience and compassion. The series blends adventure, romance, and moral dilemmas, creating a compelling tale of a heroine who defies conventions to protect her people and assert her rightful place as a leader. Through its episodic structure, "Princess Knight" delivers a mix of action, drama, and fantasy, cementing its place as a pioneering work in the shoujo genre.