Ganta Nakami is a high school student who suffers from insomnia. He meets Isaki Magari, a girl with the same condition. A relationship forms as they share a secret and catch up on their sleep in their school's abandoned observatory.

In the small city of Nanao, insomniac Ganta Nakami tries to catch a nap in his school's abandoned astronomical observatory. There he stumbles upon a sociable and carefree girl named Isaki Magari who has the same problem. The two form an awkward friendship and reestablish their school's defunct astronomy club.