After a seven-year absence, Saku Ooyagi heads back to his hometown and is reunited with his childhood friend, the exuberant Mihoshi Akeno. Yet, their reunion isn't a joyous one, as Saku vividly remembers the traumatic event of Mihoshi tumbling from a tree and his failed attempt to save her. Despite this, Mihoshi remains resolute in fixing their broken friendship and persuades Saku to join her astronomy club.