Gamu Takayama is a 20 year old member of an organization called Alchemy Star. After a monster known as C.O.V attacked the Earth, Gamu falls through a portal of light and meets the giant: Ultraman Gaia, who gives him his powers.
A jellyfish-like monster with incredibly destructive powers seems to be immune to conventional attacks
Hiroya's frustrations with humanity reach an apex as he enacts a plan to end what he sees as their futile hopes by destroying the Aerial Base. Gamu is the only one who can stop him.