The year is 2016 a year and a half after the assassination of Princess Asseylum. Despite his status as a Terran, Slaine has been granted the title of Mars Knight, is now served by his own personal subordinate, and has been taking part in battles against the United Forces of Earth. Meanwhile on Earth, the Deucalion is finishing up its repairs as, one by one, the ships former crewmembers return in order to proceed to a new battlefront.