Princess Sapphire is a girl raised as a prince. Due to the mischief of an angel, the princess is born with both a girl's heart and a boy's heart. Since there is no male heir in her kingdom, Sapphire is brought up as a boy, but wicked ministers attempt to uncover her secret. Unable to tolerate the cruel behavior prevailing in the kingdom, Sapphire disguises herself as "Princess Knight" and wields her sword of justice.
