Chibi Chibi

Chibi Chibi came into the series about the same way Chibi-Usa did.She fell from the sky floating down with an umbrella. The umbrella got caught with the wind and Usagi went and got it for Chibi Chibi. While Usagi was walking home she thought Chibi Chibi was following her but everytime she turned around nobody was there. When she got home she saw her mother with who else, Chibi Chibi! Usagi's mother asked her why she had left with out her sister. Imagine how Usagi feels especially after Chibi-Usa .

There are two theories from where Chibi Chibi came from:
Naoko- Chibi Chibi is Sailormoons future self, Sailor Cosmos. Its like Sailormoon minus UsagiOchan So she has no fear in her heart.
Toei Animation-Chibi Chibi is the light of hope form Galaxia's Starseed. So she is a form of Galaxia and is good.