What Is a Kaiju?
Explaining Yamaneon, Atomic Fossilization, and Giant Monsters

Incredible, unstoppable titans of terror. Horror hordes of crawl-and-crush giants. Neither bombs, bullets, jets, or rockets can stop them. They are living forces of nature – disasters with a pulse. They are kaiju, the mightiest monsters of all time, and they are frightfully real.

Since the first one appeared in 1954, kaiju have baffled the scientific community. They flout what we thought were laws of physics and basic principles of biology as easily as they repel our vast array of modern weapons, crushing our concept of the impossible like a car beneath their massive heels. A kaiju is not merely a large animal – it is a natural phenomenon, and one that we are only beginning to understand.

But what makes a kaiju so strange? For that we must first look at the progenitor of all kaiju: a radioactive mineral known as Yamaneon.


Like the kaiju it creates, Yamaneon is so bizarre in its nature that it borders on being ridiculously implausible. Its molecular makeup is exceedingly complex, mixing common elements like carbon, nitrogen, hydrogen, and oxygen with rarer ones like uranium – and perhaps odder still, Calcium is the most common element in the molecule. While Yamaneon’s complexity seems impractically high, especially for a naturally occurring mineral, it is nonetheless fairly common in several tunnel systems throughout the earth.

The chemical makeup of Yamaneon is only the beginning of its absurdity, however. Though no one can adequately explain how, the mineral is capable of defying gravity. A Yamaneon crystal is just as likely to float ten feet in the air as it is to lie gently on the ground, often with no apparent reason why it is doing either. It even subtly exerts this effect on others objects – the tunnel systems Yamaneon is found in are supported almost entirely by the gravity manipulating nature of Yamaneon, and would collapse in on themselves without its presence.

Strangest of all is the ambient radiation of the mineral. Though it should be impossible, Yamaneon appears to create energy – enough to nurture an entire ecosystem without the aid of direct sunlight in many cases. Large clusters of Yamaneon even glow bright enough to adequately simulate daylight, giving life to a variety of plants and animals in the tunnels made by the mineral’s other strange powers.

That in of itself would make the radiation of Yamaneon outright miraculous, but it has another affect as well: longterm exposure to Yamaneon radiation, or lacking that, exposure to a sudden burst of intense Yamaneon radiation, will turn any organic being into a kaiju.

Atomic Fossilization

Short term effects of Yamaneon radiation are subtle: an increase of vitality, faster healing, and other positive but mostly mundane effects. Long term exposure causes more advanced mutations: an organism will begin to grow in size and strength. After enough time, the affected organism’s cellular chemistry will begin to change to include more and more molecules of Yamaneon. This is particularly common in the bones of vertebrate animals and the chitin of arthropods – most full-blown kaiju have bones made almost entirely of Yamaneon.

While this process is normally slow – it takes a decade or so to complete – it can be sped up if the Yamaneon in question is made unstable. Yamaneon absorbs, converts, and amplifies any radiation it encounters, be it the energy from geothermal vents or the blast of an atomic bomb. A sudden, violent burst of energy will set off a chain reaction in Yamaneon, creating a burst of intense Yamaneon radiation in turn. This burst can turn a creature as small as an ant into a kaiju within minutes.

In the rare event where a kaiju dies, its body does not decompose as normal. Instead, its body slowly converts into pure Yamaneon. After a few hours, a kaiju’s corpse will be utterly unrecognizable, having become nothing more than a pile of glowing green crystals.


A full blown kaiju is a powerful force to be reckoned with. While they vary in size, they are on average at least twice the size of the largest non-supernatural animal, the blue whale. Even the smallest kaiju are still larger than an elephant, and the largest on record can dwarf some skyscrapers.

Size alone isn’t their strength, however. Thanks to the strange effects of the Yamaneon in their body, they can move with a speed that defies their immense size, hit far harder than they have any right to, and heal at a phenomenal rate. Kaiju shrug off most conventional weapons, and the few that do cut through their thick hides will be rendered moot as the kaiju heals from the injury within seconds. They are nigh-indestructible beasts – in fact, the only thing that has a reliable track record in killing kaiju is another kaiju. Some kaiju also have strange powers – often ones that would be detrimental to an organism that lacks their durability, such as the ability to spout flames from their mouths. Yet even those without are unstoppable juggernauts.

As for the behavior of kaiju? Well, that varies from individual to individual. To know how kaiju act, you should read up on their individual files.