At a city campsite when she was young, Mira Kinohata got to know a boy by the name of Ao. Mira discovers that while there is a star with her name, there isn't one with Ao's as they look up at the stars together. The two then make a pact to one another that they will one day go asteroid hunting and discover a star to honor Ao. A few years later, Mira resolves to keep her vow and joins the astronomy club at Hoshizaki High School. She finds out that the Earth Science Club will be created by the merger of the Astronomy Club and the Society for Geological Research. Mira reluctantly enters the club room where she meets Ao Manaka, the person she had promised would do the asteroid research. Mira is horrified to see that Ao is a female!
