I honestly expected this to be a full length series, but evidently, it's just an ONA. Which makes me wonder why the overall quality of the animation and art is so sub par. And then I remembered it's Studio Deen.
The story is based on a 3 chapter manga and shouldn't be expected to provide too many answers. The world building was sub par, leaving me with a rather vague idea of what's going on in the world. There's an opinion that the story is supposed to be about military, but I really didn't feel that that was the main focus of the story. The main
character had almost no connection with the military other than being hired. The female lead is a wolf girl. I'm not really sure what the author was really gunning for with this.
In the end, all I got out of it was a interesting idea for "humanity's next enemy" and some rather poorly animated action scenes.
The studio that made this, Studio Deen, is renown for rather poor animation quality. Most notably, Studio Deen picking up Log Horizon and taking it through the gutter. There were a lot of art problems and animation problems that really shouldn't be there for a one off ONA like this.
All in all, it's rather disappointing that there isn't anymore to the story, but at the same time, fortunate that Studio Deen doesn't get to mess up the experience some more.