The group of privateers known as the Blue Steel continues their mission to deliver blueprints of the Vibration Warhead Torpedo—a weapon that may turn the tides of war in their favor—to the United States. However, a new threat arises from their enemy, the overwhelming Fleet of Fog in the form of "The Student Council.," This is a group of warships composed of the remaining Mental Models—the ships' humanoid avatars—who have yet to face the unpredictable captain of the Blue Steel, Gunzou Chihaya.

As the Blue Steel gets closer to understanding the origins of the authority controlling the enemy, Iona's past starts to reveal why the war began and her reason for siding with humanity.