Sora no Manimani

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.
(Source: MU)