The Earth has been targeted for invasion by the alien Cthuwulf. A young girl, Nagisa Kano, becomes the key to Earth's defense when she is forced to become the partner of Iczer-One, a lone rebel who is battling the alien invaders.
Nagisa is a typical high school student on an Earth overrun by alien monsters. Iczer-3 is the youngest member of a race of fighting robot girls sworn to protect humanity. Together, they're a combat team with spunk, style and charm, but will it be enough to defeat an invading army of killer shape-shifters?