Ganta Nakami, a perpetually sleep-deprived high schooler in the coastal city of Nanao, sneaks into Kuyo High's abandoned observatory for a nap and finds Isaki Magari already there with the same idea. She is bright and popular where he is sullen and withdrawn, but insomnia unites them. Together they revive the school's defunct astronomy club, turning the observatory into a shared refuge where late-night stargazing slowly pulls them closer.