Gamu Takayama, a young genius performing experiments involving human consciousness, is drawn into a strange world where he sees a giant battling a monster; meanwhile, a wormhole unleashes a wave of invaders on Earth.

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.

Believing Ultraman to come from the Earth itself, Gamu dubs his alter-ego Gaia; a metallic organism heads to Japan and XIG moves to intercept.

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.

Gamu still hasn't let his parents know that he's a part of XIG, and he returns home for the first time in a while.

When Gamu is baffled at how the monstrous Gan Q seems to defy the laws of physics, his faulty instructions cause the XIG offensive to go wrong.