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.

Summer is swiftly approaching for sleepless high schoolers Nakami and Magari. Now members of their school’s revived astronomy club, they’re busy preparing for their first official club event, a meteor shower watch party! The city’s annual fireworks festival is also coming up, and Nakami has promised to go with Magari. Every sleepless night brings the two closer, and their first high school summer promises to strengthen their bond even more…