Kiss the Demiurge follows the story of a girl named Minori, a mage who absolutely hates magic. As a child, she wished to become a magical girl like the heroes she saw on TV. One day, a mysterious voice offered to grant her magic powers and make her dreams come true. But unfortunately, she soon came to realise that the gift of magic was actually a curse, a force of nature far beyond her control.
Minori's magic misfired and both of her parents disappeared from this world because of it. She grew up wracked with guilt and declared that she would atone for her sins by ridding the world of all those who would seek magic.
Minori investigates a fire at a local high school that she suspects to have been caused by magic. There, she just so happens to spy a poster advertising a magic club, dedicated to "Studying and spreading magic across the world."
The very concept of the club angers her and she immediately sets off to infiltrate and stamp out the members magical ambitions.