We describe here our ongoing research on modeling conceptual and narrative structure of fairytales by a computer system. In this paper we focus on the variations of fairytales based on Cinderella from all around the world. We analyzed twenty-three Japanese texts of Cinderella tales and modeled their conceptual and narrative structures using the notions of composition elements and motifs. We then incorporated all these structures into a unified structural model of Cinderella story. Finally, we implemented a computer system based on the unified structural model to automatically generate variations of Cinderella tales. The system was able to generate variations that were quite different from any of the original Cinderella tales.