Set in a futuristic world on the planet Amoi, an all-powerful supercomputer named Jupiter reigns supreme. The predominantly male human population divides into two classes: the elite with their light hair, and the dark-haired "mongrels" relegated to pet status. While wandering through the slums, one member of the elite class, Iason, discovers a captivating mongrel named Riki and brings him home as a pet. But as time passes, Iason's attachment to Riki grows, drawing unwanted attention from a society that disapproves of such relationships.