FBI agent Max Reed witnesses Dr. Tetsu Segawa - a researcher for the mysterious Chronos Corporation - being murdered. Dr. Segawa had stolen an alien device known as "The Guyver" from Chronos. College student Sean Barker, whose girlfriend's father was Dr. Segawa, finds the Guyver's hiding spot while watching the forensic team investigating the crime scene.

Sean Barker became the unwilling host to an alien bio-armor known as the Guyver. A year ago he destroyed the Kronos Corporation, an organization of mutants who want the Guyver. Now he is trying to find why the Guyver unit forces him to fight and kill evil.