In a futuristic caste society, elites keep "mongrels" as pets. An elite named Iason takes in Riki, a slum mongrel, defying norms by keeping him longer than accepted, sparking rumors of an unconventional relationship.

The story is set in the future on the planet named Amoi which is controlled by a supercomputer named Jupiter. Among the mostly male human population, the light-haired elite class is allowed to temporarily keep the dark-haired "mongrels" as pets. One elite member, Iason, encounters a mongrel named Riki in the slums and decides to take him in. However, Iason keeps Riki longer than it is socially approved, and rumors abound about their possible relationship.—AnimeNfo