Saku Ooyagi returns to his old town after seven years and becomes reacquainted with a childhood friend, the ever-boisterous Mihoshi Akeno; but the reunion is far from merry since his last piece of memory between them is of her falling off a tree and him diving to save her. Regardless, Mihoshi focuses her all into improving their tattered relationship and forces Saku to join her astronomy club.
Basically this manga is about an astronomy club, and slapstick school life comedy as Mihoshi changes Saku's life.