Saya Otonashi was "born" in 1833 from one of two cocoon-like objects taken from the belly of a chiropteran mummy, the other cocoon containing her sister Diva. Both are kept at the "Zoo" by Joel Goldschmidt, where Saya is treated as his daughter and Diva, who is left nameless, is confined to a tower. Saya does not learn about Diva's existence until 1863, when she hears Diva singing and finds her locked in a room at the top of the tower. Saya then names her Diva. In 1870, Amshel purchases a twelve-year old boy named Hagi from his parents to become Saya's companion and friend, hoping that when Hagi grows to maturity he will one day mate with Saya to create further specimens. During a birthday party for Joel, Saya releases Diva so that she can sing for Joel. Diva, however, slaughters everyone in the Goldschmidt house while Saya and Hagi are out looking for Joel's favorite flower. Recognizing that Diva is a monster, Saya spends her periods of activity hunting Diva to try to kill her, her chevaliers, and any chiropterans they have created. This is her elegant gown she wore during her years at the "Zoo".