When Duanmu Huai and his people were resisting the Demon Beast Army, Rin Tohsaka also brought everyone to her home.
"This is the core of the Spirit Vein."
Opening the door, she introduced the core of the Spirit Vein to everyone. Rin Tohsaka was inwardly speechless; she knew very well that once the Spirit Vein was destroyed, the Tohsaka family would be doomed just like the Matou family. Originally, the Matou family was a magician family from abroad, but for the sake of the Holy Grail War, they had left their homeland and come to Fuyuki City. However, since the Spirit Vein in Fuyuki City was under the Tohsaka family's control, the Matou family, having lost access to the Spirit Vein, eventually saw their bloodline grow weaker and thus lost their magician's power.
This was also the reason when Fiore moved the Furvidge, they needed a piece of Spirit Vein land. Without a Spirit Vein, the Furvidges would gradually lose their magic power and become ordinary people just like the Matous.
