The Abyssal Fleet, an enigmatic foe that has taken control of the sea, looms ahead as a crucial battle approaches in Leyte Gulf. In preparation, Kanmusu, young girls with warship souls, are tasked with defending against the enemy. Shigure, a Shiratsuyu-class destroyer, is assigned to the First Striking Force, Third Section, also known as 1YB3H. To Shigure's dismay, 1YB3H is comprised of only a few Kanmusu and acts as a mere distraction. However, they must confront the Abyssal Fleet head-on, and this may be their final mission together. Regardless, Shigure is determined not to lose another comrade to the enemy. As they embark on their suicidal mission to Leyte Gulf, the members of 1YB3H must support each other and prove their capabilities as skilled warships.