Princess Sapphire is the main protagonist in the book and tv series, Princess Knight, the deuteragonist in Twin Knight, and the character-withen the character in Philip McGhee's Osamu Tezuka and Disney manga, Prince Knight, the manga book that combines both Kingdom Hearts and Atom Cat. She later served as the mascot of PrincessKnight Productions. She is born with the heart of a girl and the soul of a man. She and Tink (known as Choppy in the tv series) often go on verious adventures in Silverland.
In Prince Knight, she served as a character only in her book; everytime Prince Knight finds a missing page for his book and reads it, her same thing from the book will appear, similar to Atom Cat.