Himea Saito  

Saitohimea, サイトヒメア / 沙糸 ヒメア

Himea possesses exceptional abilities as a vampire and develops feelings for Taito upon meeting him. Although she places a curse on him to ensure their constant companionship, she is later kidnapped by an unknown individual. Due to a magical interference, Taito forgets about his past relationship with Himea for several years until he remembers again. It's possible that Taito didn't realize Himea was a vampire because of the mystery surrounding her powers.