Meimi Haneoka seems like an ordinary 14-year-old at St. Paulia's Private School by day, but at night she becomes the mysterious and magical thief Saint Tail, a cat burglar-Robin Hood figure. She steals only from the dishonest and returns purloined jewels to their rightful owners. She learns about these injustices from her best friend, 'nun-in-training' Seira, who assures her of the morality of each assignment. Despite her virtuous motives Meimi's escapades attract the local police, whom she eludes as easily as the crooks, using a combination of supernatural powers and sleight-of-hand magic. A more challenging foe is her classmate Asuka Jr., an aspiring detective who's determined to capture Saint Tail. Saint Tail finds it difficult not to play a coy game of cat and mouse with her eager young pursuer. Will the young sleuth catch his thief or will she steal his heart?