In the future, the earth is devestated. With a larger population than the land can support, humans create a parallel world, but it collapses a thousand years later. The original world is invaded by the displaced masses and its inhabitants are forced to live on a giant airship. The city-ships youths are trained by Musashi Ariadust Academy in combat, history and politics to groom them into future leaders. However, their student council president isnt exactly leadership material, being more concerned with affairs of heart than of the state. When rumors of war and apocalypse unnerve the invaders, Masazumi Honda and his friends find themselves thrust into conflict with an opportunity to reclaim their homeland.