In the future, humanity has successfully left Earth and colonized various star systems, evolving into a new breed of humans who are taller and possess incredibly long lifespans.

Meanwhile, Earth, the once-thriving mother planet, has been reduced to a nuclear wasteland due to overdevelopment and severe pollution. The original inhabitants still living on Earth now face an average lifespan of just 40 years, leading to widespread discrimination from the new humans.

The protagonist is one of these Earth natives, but unlike others who have succumbed to despair, he works hard to become a mechanic even more skilled than the new humans. Just when he thought he could finally live a better life, he is met with betrayal and treated as cannon fodder when the cosmic insect race attacks a human outpost.

However, with a burning desire for revenge, the protagonist discovers that he has been reborn as one of the cosmic insects!