Decades after the Space Colonization Program's collapse leaves humanity on the brink of extinction, a post-apocalyptic world is ravaged by a lethal Rain. Amidst this desolation, scavengers known as 'Junkers' roam the ruins, seeking valuables. One daring Junker infiltrates the perilous 'Sarcophagus City' and stumbles upon a preserved planetarium at its heart. Within, he encounters Hoshino Yumemi, a faithful robotic companion who mistakes him for a long-awaited visitor after three decades of solitude. Despite their initial communication challenges, he reluctantly agrees to assist her in repairing the malfunctioning planetarium projector, embarking on an unexpected journey under the starlit dome.