Dr. Segawa, a researcher for the mysterious Kronos Corporation is murdered after stealing a mechanical device called "The Guyver" from Kronos. The college student Sean Barker accidentally finds "The Guyver", which merges with his body and turns him into a cyborg superhero. When the president of Chronos, Fulton Balcus, sends his mutant henchmen, the Zoanoids, to steal "The Guyver" back, Sean Barker begins to uncover a secret plot to genetically engineer monsters.