From the introduction: The year hardly seems to matter anymore. This world is one of growing chaos, war, and knives being shoved firmly into backs. An alien race has invaded the Earth. These artificial humanoids call themselves Sirens and are heavily armed enough to destroy entire fleets of warships in a single sortie. The nations of this world, still recovering from a recent war that spanned most of their world, quickly joined together to pool their resources against this threat. This coalition was called Azur Lane. User summary: A relatively lightweight tabletop implementation of the video game Azur Lane.