Princess
Kakyuu
The Starlights' princess
Kakyuu is the one the Starlights are looking for, the princess of the Kinmoku. She just appears in 4 episodes (unless you count when once a girl draw her and when her shadow appears) and is hidden in the rest of SailorStars in a chalice that Chibichibi finds.
Kakyuu is like an Usagi of another planet, but maturer. She cares for her Sailor Senshi, and even dies protecting them. You don't know her a lot, though. Usagi is impressed by her lovely personality, and helps her to stop all the Sailor Senshi when they are about to fight each other. Galaxia kills her and takes her star seed.
In the manga she is a Sailor Senshi, but dies killed by an Animamate and her star seed is taken. Her name means Fire Ball. The only attack that was seen in the Anime was when she threw a ray to Galaxia, but not strong enough. She returns to her planet after everyone is resucited, with her Starlights.