The Second Sister (Kilian II) is a protoplanet in the Kilian system, United Empire of Earth (UEE). Misshapen and low in mass, it is theorized that the Second Sister was trapped in the orbit of the First Sister (Kilian I) as it was passing through the system. The UEE Navy uses the Second Sister as a testing ground for weapons. Due to this, access to the Second Sister is restricted.