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.

The Kodomo No Omocha OVA is a thirty-minute animation video that was made before the TV series. It covers the first volume of the manga, so it's equivalent to TV episodes 1-6. It relates Sana's troubles with Hayama at school as a result of the "oyakodon baka" situation and culminates when Hayama's dad and sister realize their mistakes thanks to Sana's efforts.

As the sole survivor from a squad that was sacrificed and hung out as scapegoats for embezzlement of military resources at the end of the 100 years war, Mellowlink Arity is out for revenge. Carrying the dogtags of his deceased comrades and armed with a dated anti AT rifle, he swears to hunt down and exact revenge on the corrupt officers that betrayed his squad, and maybe even uncover the truth behind the plot as well.

The second part of the new Hokuto no Ken pentalogy. The story of this OVA centers around Yuria.