U.C. 0079. As the Principality of Zeon begins its war of independence from the Earth Federation, the brave men and women of the 603 Technical Evaluation Unit are deployed aboard the test support ship Jotunheim to gather data on new experimental weapons that could turn the tide of the war in Zeon's favor. Their first mission is to test the huge Jormungand cannon during a decisive fleet battle at Loum, but they discover that Zeon has another trump card up its sleeve.