Roy Revant, a hunter, captures a wanted man.  His partner tries for a little revenge on Roy but, just as it's looking bleak for Roy, a girl falls from the sky and Grey takes off.  Roy helps the girl out since she saved his life but in the morning he kicks her out.  The problem is, she won't stop following him everywhere he goes.  When the two partners show up once again in a huge mecha, the girl shows incredible strength in saving Roy and defeating it.