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.

The Guyver: Bio-Booster Armor is a 12 part anime OVA loosely based on Yoshiki Takaya's manga, Bio-Booster Armor Guyver. It was released in Japan from 1989 to 1992. It is the second animated adaptation, following the 1986 OVA Guyver: Out of Control.

Guyver: The Bioboosted Armor is a Japanese anime series based on the long-running manga series, Bio Booster Armor Guyver, written by Yoshiki Takaya, adapting chapters 1 - 59 of the manga. The production was in association with ADV Films and Kadokawa Shoten. The series first episode aired in Japan on August 6, 2005 and the last episode aired on February 18, 2006. The series aired in North America on December 20, 2010, on the FUNimation Channel.

Sho and his friend Tetsurou stumble upon an odd alien artifact while walking through the woods. Then, the alien artifact breaks free of its metallic bonds and enters Sho's body, turning him into the Guyver. With this new power, Sho must do battle with the evil Chronos corporation and their genetically enhanced Zoanoids, who seek to get the Guyver back into their labs. No one close to Sho is safe from Chronos. He must fight.

One night, high school student Sho Fukamachi discovers a mysterious metal object. Then in a blinding flash of light, Sho finds that he has accidentally fused with the Guyver, a mecha of mysterious alien design. Now, to save his girlfriend, Mizuki Segawa, along with the entire world, Sho must become the Guyver to fight the Chronos Corporation and their biocreatures, called Zoanoids, who are hell-bent on world domination.

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.