The plot of this OVA is a rough adaptation of the first four chapters of the Guyver manga. It covers the same basic elements of these chapters; Genesis of the guyver, Fight with Vamore, Fight with Guyver 2 and the introduction of Guyver 3. Main differences are the exclusion of Tetsuro and his replacement by Mizuki, The replacement of Lisker with a female Agent "Valcuria", and thus a female Guyver 2. There is also a look at Sho's psychology of how he deals with his situation including a very harsh moment where his friends are assassinated in cold blood.

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.

[Source: Wikipedia]

Shou and his friend, Tetsurou, stumble upon a strange orb-like mechanism, the Guyver Unit, in the woods. It physically bonds with Shou and turns him into the alien soldier, Guyver. His mission is to protect the Guyver Unit from the Japanese corporation known as Chronos. They are after it and two other units just like it. To retrieve the object, they send out vicious monsters known as Zoanoids. So no one is safe in Shou's life; not even himself.

Sho Fukamachi, a normal teenager accidentally found an alien object called Unit and thus, changed his life forever. The Unit bonded with Sho, resulting in an incredibly powerful life-form called Guyver. With this great power, Sho battles the mysterious Chronos organization and it's Zoanoids, in order to protect his friends and his world. Unknown to Sho, the battle against Chronos will lead to the discovery of the origins of human, their destiny, and the Creators...

[Source: Anime News Network]