Board Thread:Questions and Answers/@comment-1962215-20131014224458/@comment-24059841-20131017181920

The manga really touches on this concept. You should read it. In the anime it really gives a different feel to the story. Saya does acknowledge she is a chiropteran at one point but it fades away because she really wants to be human. In the manga Diva shows her love for Saya because Saya want to fight so she agrees to make her sister happy.