Kamijou Saya♀

Saya is a young girl who transfers into Yuuma's class along with her twin brother Shinya, who is also a mage. She was initially mistaken for a ghost by Hachisuke after he met up with her one night by chance at school. Her magic wand is named Sanbach (サンバッハ) and takes the form of a violin bow. They have been serving the Shikimori family (Ibuki's family) for generations. They never knew their mother because she is already dead. The reason is unknown. Them, she and her brother Shinya, wanting to see and meet their mother, urged their father to steal the Shikimori treasure for it was believed to have powers that can bring back the spirit of the dead but it turned into chaos. The treasure was provoked and unleashed the angel demons contained in it. Thus, it must be sealed again. Suzuri Minagi, Natsumi Shikimori and Takamine's mother tried to stop it. This however, ends up with Natsumi sacrificing her life to seal it and stop the demons, much to Ibuki's sorrow.

[From Wikipedia]