Every medium has it low and high points. This is a low one for anime, but its attempt to cram as much plot as possible into merely twenty minutes gets a point for trying. There are some monsters, called Ancients, who suddenly appear and seem to have a relation to the fragments of a destroyed human space explorer. The Explorer got destroyed when entering Earth’s atmosphere after coming back from Mars. To counter these Ancient there’s this group of young armored girls (whose armor still doesn’t look very armor-like, you can’t get around fan-service in some animes) and one guy (whose whining reminds me not positively of the main guy from Evangelion) in some super-duper fighting suit.
There are two battles with the enemy boss. After losing the second one and dying, he comes shortly back to life to reveal that humans are the real invaders to Earth and the Ancients are the real Earthlings. Stretched out over two hours or even a series this all might have made much more sense, but this compacted it comes over like nothing more than awful, derivative crap. Also the animation looks really cheap.