In the year 2281, the United Earth Government and the Principalities of Raia signed a ceasefire treaty, ending a war that lasted for half a century. One year after the signing of the treaty, the United Earth Government's 18th scouting party reported that the Raian capital, Melkide, has been captured by an army of unknown origin. The United Earth Government decided to dispatch an army to Raia to retake the capital and rescue its citizens. However, unbeknownst to the general public, the true purpose of this operation was to eliminate the unknown enemy and bring Raia under Earth's control.