In the midst of the Great War, Céline Dubois, a young French girl, undergoes a forceful transformation into a ship-girl. Taking on the designation of Bisson, she finds herself thrust into the turbulent conflict. Placed under the command of Adélaide Robertine, known as République, a distinguished ship-girl representing the powerful République-class battleships, Céline embarks on a journey that will test her resilience and courage.