Saya

Saya is Jin and Ragna's sister.

Information
She was bullied by Jin, but babied by Ragna. All information on her is received in flashbacks and memories. She was kidnapped by Terumi and is currently presumed dead, though this is never verified and the location of her body was never disclosed. She is the main source of Jin's jealousy toward Ragna and he is most likely the one who killed her (possibly possessed by Terumi). Noel, Lambda-11 and ν-13 are all copies of her, sharing her physical traits and some of her memories. No explanation has been given yet toward the reason for her being the basis.