This science-fiction action story is filled with high-tension as an army corps of insects plans to exterminate humans, and three insect men must attempt to stop them.
Deep under the Arizona Desert in America, a highly advanced type of insect called Gidron, creates a massive empire underground. They plan to invade the Earth and eliminate humans who they see as producing pollution. Yanma, a microid enslaved by Gidron, escapes the nest with Ageha and Mamezo in order to warn humans of the coming danger. Yanma is an intermediate creature related to both insects and humans. Although both humans and microids have the same ancestor, Yanma has been raised by insects and miniaturized.
Yanma and his team arrive in Japan to warn the humans, but only Nobel Prize winner and scholar Dr. Midoro and his son, Manabu, heed the warning.
As the insects prepare to attack, Jugger, Yanma's elder brother, and a legion of insects charge towards the humans. The death toll of humans piles up as the towns crumble one by one.
