Saku Oyagi returns to his old hometown in order to start school at Soei High School. On the first day, he runs into an old childhood friend: a second year named Mihoshi Akeno. As children, the two used to play together, with Mihoshi, or Mii-chan, being extremely fond of astronomy. After convincing Saku to join the school's astronomy club, another girl, Hime Makita, joins the club in hopes of winning over Saku. This is the story of the 6 club members of the Soei High School Astronomy Club as they soar through their lives, each maturing and changing their outlooks on life.
