He is told to go to the small island base that served as one of the front lines in fighting the dreaded Abyssal Fleet, a new enemy of humanity. He never see these new weapon called 'fleet girl'. His mission? Monitor and review their way of doing battle and also their livelihood. It is a task only the most daring could do.

Every fleet girl need an Admiral to help them perform their task. Their admiral will help them choose the best strategy and tactic to fight the mysterious and dangerous Abyssal Fleet. By following them, they can defeat anything the Abyssal Fleet throw at them and return home with a smile on their face. With that on their mind, the Abyssal Fleet is determined to do the same.