Rance 02: The Rebellious Maidens

Ten years prior to the story, four young girls in the town of Kathtom were appointed as disciples to an old mage named Ragishss. They were to be raised as mages and work as the town's guardians after their training completed. However, after the ten years, the girls suddenly rebelled against Ragishss and killed him. During the battle, the entire town was entombed underground and a barrier spell was placed on it, preventing anyone from leaving, including the maidens who terrorized the town.