Shisei: Nihohi tsuki no gotoku

In the latest film version of the novel, a dance studio's owner has a younger sister who is a university student. The owner is a good dancer herself and has won many dance contests. Her parents were also dancers. The younger sister is coy in contrast to her older sibling, but has her own dancing skills. The younger girl receives postcards from an unknown sender. She also likes to make dolls. The older sister introduces a dancer to her sister. He attacks the younger gal.