Chibi Chibi: A Child of Very Few Words
I'd like to say that, quite frankly, Chibi Chibi is a pain to research.  So, you'd better take what you can get!  If this isn't all that useful, too bad!
SO, JUST WHO IS SHE???
*Japanese Name: Chibi Chibi
*Meaning: Small Child
*Dic Name: NA
*Alias: Sailor Chibi Chibi Moon
*Birthday: June 30th (?)
*Sign: Cancer (?)
*Favorite Subject: NA
*Least Favorite Subject: NA
*Favorite Food: Doughnuts, Candy
*Least Favorite Food: ...
*Gem: Diamond
*Hobby: ...
*Dream: ...
*Favorite colors: Red, Blue, Pink, White
    Chibi Chibi has two different stories, one from the original manga, and one from the anime.
*(anime) Chibi Chibi appears in the park a lot like Chibi-usa did, and floats to the ground with her umbrella.  However, her umbrella flies away and Usagi (a.k.a. Serena or Bunny) catches it.  When Usagi returns home, her mother scolds her for leaving her sister behind, and there stands Chibi Chibi!  All Chibi Chibi can say is chibi, and a few words that she copies from others.  When she touches Sailor Moon's tiara she becomes Sailor Chibi Chibi Moon.  In the end, it turns out that she is Sailor Galaxia's Starseed! *gasp*  She came to find Sailor Moon and seal away Chaos!  Ohmigosh!
*(manga) The manga is pretty much the same except that Chibi Chibi is really Sailor Cosmos, the ultimate form of Sailor Moon, and she came to the past because she was too scared to seal away Chaos by herself.
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