Yukikadze is just a little girl, but she and her friends are incredible responsibility for being the naval power of their nation. In the composition of the Seiran 3 team, Yukikadze and her friends are heated, Novaki and Takao are present from the naval base. Sea Corps. But in this world they do not work on ships, instead, they themselves are weapons capable of traveling across the oceans at high speeds and participate in the war using their equipped artillery. When an enemy nation attacks the base to take control of an important strategic point, it remains only Yukikadze, and all hope seems lost when a beautiful woman named Taiwan appears with secret weapons to protect Yukicadze and naval base.