Chibi Usa was first seen in the Sailormoon R series. She dropped out of the sky when Usagi and Mamoru were on a date. She then attempted to take Serena's Imperium Silver Crystal by holding a toy gun to her head, and since then, the two have never really been on each other's good side. Reenie is in fact, the daughter of Sailor Moon. In the 30th century, the city of Tokyo was known as Crystal Tokyo. When the Dark Moon Kingdom attacked Crystal Tokyo, Queen Serenity (the future of Sailor Moon) was hurt, encased in layers of crystal, and put into a deep sleep. Chibi Usa then went to the past to request help from Sailor Moon, who she had learned from her father, King Endymion (the future of Tuxedo Mask), was the strongest senshi of all time.

Once, under the spell of Wiseman, Reenie was transformed into Wicked Lady. This made her age nearly 10 years and possess potent powers. She was eventually transformed back when Sailormoon and the other scouts began to show her love and affection. Only then, did she remember her former self as Reenie.