Cinderella from the Dungeon

In a world where magic is forbidden, I ended up as a prisoner of a dark mage. He used me in his secret experiments and turned my life into hell. Then a “buyer” appeared for me—a powerful and mysterious man. Now my life will change… But what kind of changes are these? For the better or for the worse? And most importantly, who is he, and why am I needed by him? How can I become free and happy if I’ve turned into a bargaining chip in forbidden magical games?