In Uni-5 the planet robots are invading, the cause, the heart of the beast a orb that is blue and is see through. But who is there to stop them the anti robot corps they use weapons to kill robots and there are the 4 main ARC (anti robot corps) they are the most powerful ARC weapons wielders. But who is the main character you may ask well he is part of the 4 ARC his name is Grey the chosen one to weild the chosen sword.