Blood+

Saya, the main character, lost her memory and has been living with her adopted family. Her everyday life seems quite normal, except that she eats a lot more than she actually needs. Then one day she meets a guy named Hagi in a park. She is told that he has been searching for her, for a long time. Since then, her normal life has changed completely. (This manga series is proceeding quite a bit differently from the anime)