The Tohsaka, a lineage with a history of about 200 years, they were once Hidden Christians that lived inside a then foreigners-intolerant Japan. Their first head, Nagato Tohsaka, was considered the least promising of Zelretch’s pupils. But by six generations after, the time of Rin and Sakura, the family had improved to the point of reaching second place. They possess good connections in both the Mage’s Association, due their relationship with Zelretch, and the Holy Church, thanks to their faith.
The Tohsaka are experts in the use of Jewel Magecraft and a secret style of Chinese kenpo, the latter due Nagato’s emphasis in the training of not only Magecraft, but also martial arts. Thanks to the sudden and relatively recent progress of their mastery of Jewel Magecraft, as well as the introduction of the Gandr into their magical repertory, it is believed that the Tohsaka lineage was able to incorporate the Edelfelts’ knowledge of Magecraft into their own through the younger Edelfelt twin that was supposedly defeated during the third Heaven’s Feel, for members of that family (such as Luvia) are well known for being very capable in the use of both. It is unknown if the Tohsaka gained the abilities from the Edelfelt twin marrying with the head of the Tohsaka family of that time or simply by having her Thaumaturgical Crest stolen.
Back when the Tohsaka were developing the ritual of the Heaven’s Feel along with the Makiri and the Einzberns, Nagato’s daughter played a greater role in the completion of the Holy Grail War system than her father. The Tohsaka role in Heaven’s Feel is to provide the use of their spiritual land to the ritual.