While walking in the forest with his best friend Segawa Tetsuro, Fukamachi Sho, a Japanese student, accidentally discovers an ancient alien weapon known as a 'Guyver Unit.' The Guyver Unit consists of a symbiotic bio-boosted armor, created by aliens that visited earth centuries ago. The insidious biotech corporation known as Chronos has kept it secret for years. Now that Sho has found it, he and his friends are hunted by Chronos' monstrous creatures as the corporation seeks the return of the Guyver for their twisted experiments.