Tohsaka Aoi

Tohsaka Tokiomi's wife, and Rin and Sakura's mother. Her maiden name is Zenjou.
Though the Zenjou family had a magus ancestor many generations ago, now they are simple commoners with no connection to the magical world at all. Nevertheless, the blood flowing through their veins contains a very
unique trait, which was noticed and pursued by Tohsaka Tokiomi. As a result of accepting this courtship, Aoi gave birth to two sisters with absolutely preposterous magical potential.
Unlike her daughter Rin, Aoi fully understood that Tokiomi possessed an inhuman sense of values, but she still blindly loved her husband anyway. Maybe she, too, bore some distortion within herself, just like Tokiomi did. If that's the case, she probably wouldn't have been able to build a happy home even if she had married Kariya…
By the way, the activation of Tokiomi's “Tohsaka family goof-up trait” only occurs in serious, life-threatening situations. In his normal family life at home, he was an utterly perfect superman, in the same way Rin would eventually be a perfect honors student at Homurahara Academy in Fate/stay night. I hear that both Aoi and Rin were huge fans of his “cool dad” style.

Fate/Zero material: Fate/Zero Encylopedia