Agon, being reptilian is cover in scales which become lighter towards the inner part of his body. His head somewhat resembles that of a Gila monster, but with short spines coming from the top and back. Similarly, he possesses sharp, curved claws at the tips of his webbed fingers.
Agon's presence is first made known when Dr. Ukyo's Geiger counter begins detecting massive amounts of radiation nearby. Suddenly, Agon rears his ugly head from the surrounding waters, creating a spout of bubbling foam. He lets out multiple blood curdling roars as Goro begins snapping photos. He starts toward land, frightening the onlookers and urging them to duck under cover. Luckily, the supposed monster attack transitions to a mere sighting as Agon disappears into the foam once more. The encounter does not go unheard however, with Goro's pictures being published in the newspapers and making headlines everywhere.
A short time later, Goro and Detective Yamato are summoned by Dr. Ukyo, in the hopes that he can better explain the monster's motives; not without interruption however from a certain stubborn canine. Once they finally arrive at the National Atomic Energy Center, Dr. Ukyo explains that according to a biology report, Agon was a kind of dinosaur which originally roamed the Earth during the Jurassic period and has become mutated. After further questioning from Goro, Ukyo also reveals that it is very possible Agon could have remained dormant underwater and became irradiated by nuclear bombs. But, their conversation is cut short by an urgent call which turns out to be notifying the lab of an abnormality shown on the Uranium storage checking meter. As the warning lights begin to flicker, Dr. Ukyo realizes what the anomaly really is, and immediately tells the others to follow him. He sprints toward the beach as fast as he can with his partner close behind, Geiger counter in hand. Just as they step foot on the sand, the Geiger begins to detect radiation once more.
Sure enough, the ground begins to quake and the water begins to bubble as Agon appears. With a bellowing screech, Agon trudges to land, with the humans trying to escape his wrath. Ms. Shizukawa, who broke away earlier to call for the Defense Force, soon comes face-to-face with Agon who bursts through a patch of trees. She does her best to escape, but trips on a tree root and is trapped under a log which Agon knocks over. As he makes his way through the forest, he claims multiple victims, notably by more falling trees. Agon's appearance breaks out complete mayhem as surrounding town residents run for their lives. Meanwhile, Ms. Shizukawa is still in peril; but, the utter force at which Agon's gigantic feet pound the ground as he walks is enough to split the Earth wide open, trapping and instantly killing her.
Agon's most icon, and arguably most devastating ability is his atomic flame breath, acquired from nuclear radiation. It has limitless power and can mow down entire towns within seconds of its use, but is surprisingly rarely used.
Although not aquatic in nature, Agon is an adept swimmer and is speculated to have laid dormant underwater since the Jurassic period. He seems to spend most of his life underwater, constantly seen appearing from and returning to the water.
- Main article: Agon/Gallery.
- Agon bears an uncanny resemblance to Godzilla, so much so that Toho prohibited Nippon TV from broadcasting Agon: Atomic Dragon for four years until they were finally convinced that the resemblance was unintentional.
- Agon's suit was reused twice in the series Ambassador Magma, first as a generic dinosaur and then as the fire-based monster Aron.