Mild-mannered high school kid Sho Fukamachi and his sweetheart Mizuki Segawa accidentally come upon a strange object that suddenly bonds itself to Sho. It's a bio-booster unit known as a Guyver ... and the Chronos Corporation is willing to kill to get it back. They kidnap Mizuki in an attempt to blackmail Sho. Furthermore, Chronos has trained one of its own agents, the athletic Supervisor Valkyria, as Guyver II, and they are set on a collision course that is bound to get ... out of control.
The 3 Guyver units are stolen from the enigmatic Chronos corporation in Japan. A high school student named Sho Fukamachi accidentally discovers Guyver 1 and triggers the control metal. He becomes the Guyver and battles biomorphic Zoanoids controlled by Chronos.
Lisker, an agent of Chronos headquarters, unwittingly joins with Guyver 2. He abducts Sho and his friend Tetsuro in an attempt to locate the other missing units. Sho summons the Guyver and the two are thrust into a deadly battle for survival!
Commander Guou arrives from Chronos headquarters to lead the recovery of the Guyver Units. Meanwhile, Chronos Japan creates the Zoanoid "Zerububuse" in a final desperate attempt to eliminate the Guyver. To bait the trap for Sho, Mizuky is kidnapped and Sho once again must become the Guyver and face the challenge of Zeruububuse as well as the mysterious shadow, Guyver III.
Commander Guou takes full control of Chronos Japan and deploys his Hyper-Zoanoids against Sho. Together with Tetsuro, Sho tries to expose Chronos but the media won't believe their story. In order to force out the Guyver, the Hyper-Zoanoids attack Sho's school.
Chronos Japan transforms Makishima into Enzyme, a powerful Zoanoid created to eliminate the Guyver. To force a confrontation with Sho, Commander Guou again kidnaps Mizuky and Tetsuro. They are taken to the mou ntains and forced to watch as Sho and Enzyme battle in a fight to the death!
Tetsuro and Mizuky are held hostage at Chronos headquarters. Meanwhile, Guyver III's identity is revealed as he initiates his plan to destroy Chronos. Will Guyver regenerate in time to save Tetsuro and Mizuky?!
Agito meets with the Chronos scientist Dr.. Balcus. Later, Sho grieves about his father's death while his friends Tetsuro and Mizuky are kidnapped by Chronos. Again the trap is set to capture the Guyver!
Sho heads for Mt. Minakame in search of friends. During the journey he confronts the "LOST UNIT" (a monstrous Guyver) and other villainous Zoanoids.
Sho discovers that his father is alive and attempts a daring rescue to save him and Mizuky. Balcus, knowing what Sho will do has set a trap to capture the Guyver.
The tragic clash with Enzyme II has affected Sho's ability to transform into the Guyver. When everyone tries to escape Mount Minikami by going through Takeshiro village, they fall into Balcus' ambush.
Murakami reveals the origin and purpose of the Guyvers and Zoanoids. To rescue Guyver III from several Enzyme II creatures, Murakami must expose his most guarded secret.
Sho must transform into the Guyver to save Mizuky from Aptom. However, his inability to bio-boost may cost them their lives.