[2] The Chronos Corporation has secret plans for the world and have biologically engineered employees and soldiers who are able to transform themselves into powerful monsters at will, beings called Zoanoids.

A test type Zoanoid, disguised as a normal man, escapes after stealing a bag containing three items Chronos was studying, known as the Guyver units.

Shō accidentally activates the unit and it merges him with the biological armor, increasing all his physical abilities and arming him with deadly weaponry.

Determined to recruit Shō or recover the Guyver armor from his body (even if removing it proves fatal,) the Chronos Corporation begins sending Zoanoids after the teenager and his friend Tetsurō.

The Zoanoid attacks lead to escalating battles that result in Shō learning to be a deadlier warrior while uncovering more of his armor's abilities.