Kisa the Cat is an Icelandic fairy tale collected in Neuisländischen Volksmärchen.
Andrew Lang included an adapted version in The Brown Fairy Book.
Many years later, the princess was playing with a ball and threw it farther than usual; then she heard a voice calling her, and saying she was Kisa her sister.
Then Kisa reappeared and asked to sleep at the foot of her bed on her wedding night.
She told how she and her mother had been enchanted by a spiteful fairy, and she lived in their castle until she married a prince herself.