Rosemary is Thief Lucifer/Eimi Haneoka's rival when Meimi's mother was still a thief. When she discovers that Eimi Haneoka/ Thief Lucifer is living a normal life with a husband and a daughter, she decides to seek revenge on her daughter, Meimi Haneoka, instead of her because she thought that a Daughter's Pain is a Mother's Pain. She uses Jade Dust to cause powerful hallucinations. She adopted a girl named Maju to be her daughter. But after seeing Daiki Asuka Jr. proving that he truly loved Meimi Haneoka/Saint Tail no matter who she was, she decided to stop her revenge as she was touched. Rosemary also said, "If I had met a man like him 20 years ago, I would not have turned out like this..."
She leaves for the next town to make money at the last episode.