The Saint's Magic Power is Omnipotent (Light Novel) Vol. 3 (Kobo eBook)
The Saint's unique magic dwells within Sei, though she lacks full control and doesn't know why. She finds distraction in a sanctuary for rare herbs, where she can indulge her real passions. But the truth always catches up with Sei in the end, and this time, it will come through the words of a former Saint herself.