In the near future, a shift in the world's climate created a perpetual super cyclone in the Western Pacific: the Grand Roar, which altered the earth and flooded most countries. Shipping and navigation became vital to nations, and following the emergence of ocean pirates, companies were necessitated to hire escort cruisers to safeguard their investments. Hyousuke Nagimiya is a system engineer commissioned to upgrade the Pascal Magi, a vessel manned by an all-female crew with Misaki Nanaha as captain. Together, the crew strives to prove to their detractors that they are no mere 'Alice Brand'. Yet, as they carry out their mission, a larger global conspiracy seems to be working behind the scenes to take advantage of this new world order.