After a catastrophic event decimates humanity, four survivors, including the gentle Masashi, the timid Sanae, the daring Yaeko, and the young Anna, come together in a serene existence. Living in a semblance of post-apocalyptic tranquility, they await the return of others. Yet, their peaceful routine is disrupted as they uncover lingering remnants of the enigmatic 'Phantoms,' hinting at a deeper mystery about Earth's fate. Will they unravel the truth behind their planet's tragic downfall?