Mari Hayase is the daughter of a scientist, Eiji, who vanished three years ago. He left behind a pendant known as the armillary compass. One day, after coming across a mysterious book, the compass glows and sends Mari back in time. Supported by her best friend Waka Mizuki and Waka's brother Shun, Mari travels through time in search of her missing father and along the way meets prominent scientists who changed the way people think about magnets & electricity.

(Source: Wikipedia)