Chibi-usa is a five year-old child of Neo-Queen Serenity and the King of the Earth from 30th century Crystal Tokyo. She comes to the 20th century to search for the Imperium Silver Crystal and to escape from the Negamoon family. She is quite intelligent and articulate for her age, and initially presents herself as obnoxious, spoiled, high-spirited, rude little girl. It is later revealed that this is a front - in reality, Chibi-usa is lonely, scared, and harbours a tremendous secret. Chibi-usa has tried to repress the memories of what happened after she took her mother's Imperium Silver Crystal, but this is ineffective and Chibi-usa often experiences flashbacks. She tests the love and friendship of others and tries to push them away with hurtful words and actions, including running away from Usagi's home multiple times. Chibi-usa may not feel worthy of being loved, or wants to hurt others before they can hurt her. After she has tested Chibi-usa's and the other Sailor Senshi’s love for her, Chibi-usa reveals a new personality.  She is curious, brave, energetic, and extremely helpful. Chibi-usa offers to do all of her housework when Usagi’s mother is sick, and even plays nursemaid to Usagi. Although Chibi-usa and Usagi often argue and bicker, they usually sleep in the same bed. Additionally, Chibi-usa shares a special bond with Mamoru and is extremely focused on her quest to find the Imperium Silver Crystal. It is not until much later that Chibi-usa discovers that Usagi and Mamoru are younger versions of her future parents.

 
Sailor Chibi Moon