Under the care of her adoptive family, Saya Otonashi has been living the life of an anemic and amnesiac, but otherwise ordinary schoolgirl. Saya's happy life is shattered when she is attacked by a chiropteran, and learns that she is the only one who can defeat them. Chiroptera is the name of the order of biological classification that bats are in (this is the most likely reason for the vampiric creatures being called "Chiropterans"). Armed with her sword, Saya embarks on a journey with her family, allies and faithful servant, Haji, to rid the world of Chiroptera and rediscover her identity.The series is initially set in present day (September 2005) Okinawa City (Koza), on Okinawa Island, near the US Kadena Air Base. In the course of the series, Saya visits locales across the world, while fighting enemy chiropterans and searching for her origins.
while this is a romantic story about devotion. this also is a story about family and what it means. one sister was given the chance to grow while another was locked up in a cage. both grew to understand humanity in two different ways. not human not monster somewhere in the middle. the two sister live through the years fighting monster and themselves finally understanding what family really means