The "rounds" are humans with the sex organs of both genders. Artificially created to test the limits of the human body in space, they are now a minority, despised and hunted by the terrorist group Vessel of Life. Aboard Zeus I, a space station orbiting the planet Jupiter, the "rounds" have created their own society with a radically different view of gender and of life itself. Security chief Shirosaki keeps the peace between the "rounds" and the typically gendered "mono," but when a terrorist strike hits the station, the balance of power and tolerance is at risk, and an entire people is targeted for genocide..