Sailor Chibi-Moon is a pink-haired girl. Her name is Chibi-Usa(Rini). Rini is the child of Prince Darien/King Endymion and Princess Serena/Neo-Queen Serenity from the far future. Rini is sent from Crystal Tokyo by her mother (Serena Tsukino). Crystal Tokyo has come under attack and in order to ensure that Rini will not be hurt, she was sent back to the past to find her mother as a teenager and get the Silver Emperial Crystal from her. The Silver Emperial Crystal's Power is the only thing that can save Crystal Tokyo.

Rini is alot like Serena only more of a brat and Rini and Darien become instantly attached but they don't know that they are related. Rini's robotic pet cat-The Luna P-Ball takes place as a protecter for Rini, a replacement for the real cat-LUNA. The Luna-P Ball also serves as a multi-purpose tool (like to drug the girls!) The key that Rini wears around her neck allows her to travel through time though it is a very "dangerous" thing to do.

Her name is meant to be short for SERENA. In the original storyline, Chibiusa was named after her mother-Usagi. Chibi means small and Usa is short for Usagi. The reason why she is called Rini and not "Serena" is not to confuse the two. Rini before coming to the past lived in the 30th century into the future. Rini appeared (dropped?) out of the sky and landed on Darien's head. That was episode 54-Serena Times Two. Rini reappears in Sailor Moon S as her mother sent her back for some training.