Nuclear testing triggers the sudden evolution of the Fumoon, a tiny but highly intelligent humanoid species that emerges on a small island. Dr. Yamadano discovers them, but only a handful of witnesses, including detective Shinsaku Ban, young men Rock and Kenichi, and Kenichi’s sister Pichi (Pinoko), believe his account. The Fumoon begin kidnapping animals from around the globe to bring aboard their spacecraft, planning to evacuate Earth as a black‑gas cloud from a stellar explosion threatens to destroy the planet. While the Fumoon intend to abandon humanity, one of them, Rokoko, befriends Kenichi and works with Dr. Yamadano and others to develop a plan to save the world.