After a tumultuous battle, the rebellious Musashi has been vanquished, and the Yokosuka Girls' Marine High School students have returned home unscathed. However, the Harekaze suffered grave injuries in its clash with the Musashi, casting doubt on its future voyages. Whispers of the Harekaze-class disbandment echo through the corridors as other factions eye its crew members. Amidst this uncertainty, hope flickers in the form of sealed directives entrusted to the Harekaze's secretary, Kouko Nosa. With time slipping away, the crew anxiously awaits the contents of these mysterious orders that might hold the key to their ship's salvation.