Yū Morisawa is an ordinary 10-year-old girl, until she sees a spaceship floating in the sky. Carried into the ship, she helps Pino Pino find the Feather Star. In thanks for her assistance he grants her a magical wand, which allows her to transform into a 16-year-old girl, for one year. She is also given two cats from Feather Star, Posi and Nega, who are to watch over her while she has magical powers.