Earth has been devastated after a war between humanity and an AI unit called Artemis 20 years ago.
One day, a mysterious young girl codenamed ＂Empress＂ wakes up in a laboratory. She has no recollection of who she was, that only she was known to be one of the saviors of mankind, along with 2 others. She then learns of Artmeis' next move to conquer Earth: a bridge between the planet and the moon. Will Empress be able to stop this plan? Will she learn more of her past? And what sort of allies will she make along the way?
This is the story of a young girl known as... Black Rock Shooter.