She was the ant he trampled to death. She hated him in ten reincarnations, but fell in love with him. She defended him and died, and he waited a hundred years to become a demon. She cultivated her Buddha body and came back to enlighten her - "If you are unwilling to look back, I will accompany you to become a demon."
It's not a holy monk saving a witch. It is the ants who become Buddhas and enlighten the demons.
