(This novel can be read as a blend of Warship Girls R and World of Warships.)
In September 2014, a massive force of Abyssal shipgirls suddenly appeared in the oceans of Earth in a parallel universe. They were born from the steel of warships that had sunk in the past, and wielded powerful ship equipment. Humanity set aside its differences and united to fight back, winning several costly victories thanks to its technological advantage. But resources were running out. Just then, science gave humanity a wonderful gift: shipgirls.
Meanwhile, someone from another parallel universe got caught up in all this by a strange twist of fate.
