Unable to sleep at night, Ganta Nakami is cranky in class and unpopular with his classmates. He discovers that the school observatory, once used by the now-defunct astronomy club, may be the perfect place for a nap--but he's not alone. Fellow insomniac Isaki Magari is willing to share the observatory with Nakami, and a friendship between the two begins as they bond over the most unlikely things.

As stargazing season arrives, Nakami and Magari dive headfirst into their club activities, preparing for the Geminids meteor shower observation and planning a trip to capture Noto's starry skies. However, unexpected circumstances arise, and they must instead look forward to Magari's birthday and a peaceful, snowy Christmas.