The central character of the series is Saya Otonashi, a seemingly ordinary teenage girl who was adopted a year before the series begins and who has amnesia. Her life is dramatically changed when she learns that she is a chiropteran—a vampire-like creature—who was born in 1833, that survives by drinking the blood of others or receiving it through blood transfusion, and is the only one who can destroy other chiropterans and her twin sister Diva. Saya and Diva are the "queens", the first and more powerful of chiropterans which are always born as twin females. Aiding Saya in this century long quest is an organization called the Red Shield, with a man named David assigned to be Saya's primary "handler." With Saya forced to return to her former life, she is reunited with Hagi, her chevalier—a sp