Saya Otonashi

The Blood+ anime, light novel, and manga series features an extensive cast of characters designed by Chizu Hashii and created by Production I.G and Aniplex. The series is set within fictionalized versions of various real-life cities, including Okinawa, Japan; Hanoi, Vietnam; Yekaterinburg, Russia; Paris, France; London, England; Fayetteville, North Carolina; and New York City

The central character of the series is Saya Otonashi, a seemingly ordinary teenage girl who was adopted into the family of Kai and Riku Miyagusuku a year before the series begins and who cannot remember her past. Her life is dramatically changed when she learns that she is a chiropteran—a vampire-like creature—who was born in 1833, 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 descendants of a line of supremely powerful chiropterans that 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 special form of chiropteran created by feeding a human the blood of a queen which causes a powerful bond to form and compels the chevalier to serve and protect his queen at all costs.

As the series progresses, it is revealed that Diva has five chevaliers to aid her: Amshel Goldsmith, Solomon Goldsmith, Karl Fei-Ong, James Ironside, and Nathan Mahler. They have formed their own organization, Cinq Flèches, which they use to create additional chiropterans from Diva's blood. Working against both sides are the Schiff, a group of escaped artificial chiropterans created by Diva's group who attacks both sides in search of the blood of Saya, Diva, or one of their chevaliers in hopes that one will be the right blood to save them from a fatal and painful disease they call the Thorn.

...
Wikipedia