Blood+, Volume 2 (Manga) » (Bargain)

Saya seems, from all appearances, to be an ordinary teenage girl suffering from amnesia. Living with a foster family just outside an American military base in Okinawa, Japan, she soon discovers that she is anything but normal. She learns she is an apparently immortal warrior, who has ties dating to ancient Egyptian times if not earlier. For centuries she has been locked in a battle against a race of vampiric creatures known as Chiropterans, monsters that seem intent on destroying all life on Earth.

In an epic tale that crisscrosses the globe from the streets of Japan to Vietnam, Russia, France, England, and ultimately North Carolina and New York City, Saya battles to save the world while searching for the secret of her lost memories