The Little Mermaid
As it happens, she sees a human prince and falls in love with him. She wants to meet him again; however, she is a mermaid, and her father, who is the king of the sea, would not let her do so. She wants to find a way to win the prince's love, so she goes to the sea witch's cave. She will get an immortal soul if she wins the love of a human. She sacrifices her voice and her tail to the sea witch for two human legs. The prince becomes her companion. But, he falls in love with another person. The mermaid has the chance to return to the sea. She must kill the prince to go back, and so she refuses. She dies, and is transformed into a daughter of the air. She will receive an immortal soul if she does good deeds for three hundred years.