Princess Knight (1963)

Sapphire is the Prince of Silverland - however, Sapphire is actually a girl. At birth, she was born with both a boy's heart and a girl's heart thanks to a prank pulled by the cherub Tink. Her parents, without a son, decide to raise her as a boy, and even dress her as such.

Several plots threaten to undermine not just Sapphire, but Silverland itself. Can Sapphire keep her homeland safe?

Note: Different from the 1953 version that was serialized in Shojo Club. This version includes characters (like Captain Blood) that were not in the previous version, as well as a different plot.

Volumes 4-6 of the Osamu Tezuka Complete Works