The time is the Middle Ages.
The human world is infested with demons, and people are living in a desperate time.
At Tesca Nahal Church, which was established to combat this threat,
Noelle undergoes a trial to become a Preces (senior nun) with various thoughts and feelings in her mind.
However, at the same time, two Metuses (upper class succubi) descended on earth,
and further chaos was taking over the human world...