A strange man is on the run from an army of soldiers and it seems he has stolen 3 strange devices. This man and the soldiers are all Zoanoids; monsters created by the sinister Cronos corporation. The Zoanoids battle and there is an explosion which scatters the 3 units. Sho Fukamachi is a normal high school student who goes to school with his best friend Tetsuro, and had a crush on Tetsuro's sister Mizuki. On their way home school they take a shortcut and stumble across a strange, orb-shaped, device. Tetsuro accidentally activates the device which seems to tranform into a creature that covers Sho, who then falls into a lake. Before Tetsuro can help him the Zoanoid soldiers show up and attack Tetsuro. Before they kill a strange being rises from the lake and destroys the monsters. It is Sho, who has been transformed into the Guyver, his life will never be the same again.