Katsuki Mai is the young daughter of a couple who run a small snack shop, while her grandparents lead a troupe of stage magicians called the "Magicalettes". She idolizes a legendary stage magician named Emily Howell and, when her grandparents move in just down the street, she seizes the opportunity to follow in her idol's footsteps. Unfortunately, since she's young and inexperienced (and clumsy, to boot), she's not very good at magic tricks, although the troupe is happy to let her help out, and even allow her to appear on stage as an assistant for their act.
While helping her grandparents move in, she notices a strange, floating light (a Will 'O Wisp) and follows it upstairs. There, she sees many lights appear INSIDE a mirror, along with many reflections of herself. Suddenly, a bracelet appears on her wrist, and a stuffed flying squirrel named Topo comes to life and explains to her that the bracelet is a gift which will allow her to transform & do REAL magic.
One day during a performance, Topo causes a disaster, and Mai has no choice but to transform into Magical Emi (a name she chooses in honor of her idol) a young woman with short green hair who amazes the crowd with feats of magic, and saves the show. Magical Emi is also seen by a TV producer named Kogane-san, who happened to be in the audience. He runs JTV, and soon contracts the troupe (including Magical Emi) to appear on his TV station. Mai strives to achieve her dream of becoming a REAL stage magician, without the "cheat" of using real magic to perform her tricks.
This was the third of the four famous 1980s magical girl series created by Studio Pierrot, those being Creamy Mami, Pelsia, Magical Emi, and Pastel Yumi.
Edited from shoujo.tripod.com/emikasha.html