A tiny alien race born from nuclear fallout decides Earth is finished before anyone else figures out what's happening. A detective and a handful of kids are the only ones who believe it, fighting to save a planet nobody thinks needs saving. The real horror isn't the Fumoon, it's that they're right, and nobody cares until it's too late.
A stellar explosion sends a wave of black gas hurtling toward Earth, and only one scientist knows the truth: Dr. Yamadano has discovered the Fumoon, a superintelligent alien species evolved on a remote island, preparing to evacuate before humanity's extinction. When no one believes his warnings, Yamadano teams up with detective Shinsaku Ban and two young locals, Rock and Kenichi, to uncover the Fumoon's desperate plan. The aliens are methodically collecting animals from across the globe, loading them onto spacecraft for their escape. Mankind, it seems, has been deemed expendable. But Rokoko, a Fumoon who forms an unlikely bond with Kenichi, rebels against this decision. Together with a handful of believers, they race against time to construct a ship that might save at least some humans from oblivion. What begins as a desperate plea transforms into a race for survival, where trust between species becomes humanity's only lifeline. In the shadow of cosmic annihilation, one alien's compassion becomes the difference between extinction and hope.