Centuries have passed since humanity ceased to be the masters of Earth.

Following the invasion by the alien race known as the Astraea, Earth was remodeled into their new residential planet.

Giant cities that traverse the sky. Perfect bodies free from disease and aging. The artificial intelligence "Meter" that manages all information.

And in the corners of this perfect world, humans are called "Hybrids."

Those stripped of freedom and driven into slums. Those used as labor. And those who are beautiful or rare—are bought as "pets."

For the Pleia, keeping humans is nothing out of the ordinary.

At parties, they show off their pets, appraise their value, and sometimes let them play together.

Never doubting for a moment that humans are their possessions.

—Something that those living in a perfect world can never possess.

It was "life"—the act of being wounded, frightened, angry, exhausted, and yet still trying to live.