From the introduction: Welcome to the world of Heaven’s Lost Property! The world is much like the one you’re familiar with, but orbiting the blue planet Earth is a UFO hidden from the eyes of those below. This circular metropolis is Synapse, a highly advanced civilization of winged cousins to humanity, who look upon their “Downer” earthly kin with scorn from their own Heaven. Within Synapse, all physical needs are satisfied and the residents within live ageless utopian lives. Among their inventions are the sentient androids known as Angelroids, programmed to act as loyal servants to their Masters. They function as both laborers and personalized weapons, especially in the hands of the sadistic dictator of Synapse: Minos.