Saya Otonashi
High school senior Saya Otonashi doesn’t remember anything that happened before one year ago. Despite the lack of memory, she lives a happy life with her adoptive family--that is, until a blood-sucking vampire called a “chiropteran” attacks her and her brother. The attack triggers the unraveling of her past, and Saya soon discovers that she is the only one who can defeat the chiropterans. With the help of her family, friends and her faithful servant, Hagi, Saya starts to revisit her past life and accepts her role battling the vampires that have plagued Japan for centuries.
Haji
A handsome cellist with some alarming Chiropteran features, Haji presents Saya with the special sword she uses to kill Chiropterans. He is somehow tied to her forgotten past.
David
David is a member of Red Shield, an organization formed to track down and destroy Chiroptera.
Riku
Saya's younger adopted brother. He's a smart and obedient boy with a fondness for cooking.
Kai
Saya's older adopted brother is one of the most popular students at school, a former baseball star. He is very protective of both his siblings.