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.

After disobeying Magari's parents, Nakami and Magari face a strict separation. Magari is banned from having any contact with Nakami beyond school. Overwhelmed with guilt, the duo reluctantly agrees to put their connection on hold. At the same time, the astronomy club faces disbandment, and the pair must make a bold move in an attempt to save it. Can Nakami and Magari defy the odds to salvage both their relationship and the future of the astronomy club?