This will be a companion question for How plausible is my monster?. My previous question dealt with a story treatment for a hard science and realistic take on Kaiju/ giant monsters. While that story does feature Kaiju genre elements, it's really more of a western take on a monster with heavy implementation of classic horror tropes. On the flip side of this is a story idea I had along side the above mentioned story around the same time- a full fledged traditional Kaiju story.

Unlike western monsters, Japanese Kaiju are often times god-like in nature and behave more like forces of nature rather than animals. Often times possessing some sort of breath weapon or at least some form of natural (or rather unnatural) directed energy weapons. They more often than not possess hide extremely resilient to conventional weaponry and overall are seemingly impossible abominations whose tamest spit in the face of all known laws of science and physics. As such in this universe we'll likely never have to worry about a Godzilla like organism rising out of the sea and ravaging our cities...but what if one did?

What if an impossibly huge beast crawls out of the ocean and doesn't crumble into a pile of organs and broken bones the moment it takes a step on land? Not only is it walking around just fine but it apparently isn't even fazed by bombs or missiles. How are its bones not shattering with every step? How is it able to withstand its own internal pressures? How is it able to properly regulate its body temperature? Any answer to my previous question had to rely on at least speculative science and up to very convincing pseudoscience to work, as giant monsters past a certain size or power level are going to inevitably be implausible. And that's fine, good stories don't need to be realistic as long as they follow their own internal logic.

To make this a little easier I'll give a brief description of the creatures.

  1. The Kaiju range from 100 to 600 feet tall

  2. They have no set morphology and come in varying shapes and sizes, as a group appearing to be comprised of creatures that vaguely resemble monstrous fish, reptiles, and even mammals and birds

  3. The Kaiju's skeletons are light weight but are stronger than any metal known to man

  4. Each Kaiju is powered by an integral organic nuclear engine

  5. Most Kaiju can fire a particle beam from their mouths

  6. The Kaiju hide is super tough and resilient

So my question is this: Without resorting to magic or making them alien constructs, what sort of Applied Phlebotinum can I add to my story to convincingly explain away the above attributes and the common problems a Kaiju would realistically face in real life?

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    $\begingroup$ I'm afraid you've already answered the question yourself. We can't really explain Kaiju with any remotely realistic science. You can pick and choose between established varieties of phlebotinium or invent you own. However it all comes down to wether your story is interesting enough to make the reader/viewer simply accept that they are there. $\endgroup$
    – Guran
    Aug 19, 2016 at 6:03
  • $\begingroup$ true, in hindsight I don't really know what I was really thinking with this question. My apologies. $\endgroup$
    – SolidG
    Aug 19, 2016 at 6:46
  • $\begingroup$ No problem. Maybe you could rephrase it, as a specific question about what brands of phlebotinium are useful today, generally.. But that is more of a writers questin than a wb one. $\endgroup$
    – Guran
    Aug 19, 2016 at 6:59
  • 1
    $\begingroup$ This question, as it stands, is way too broad and, more specifically, you're looking for Idea Generation, which we do not do here. $\endgroup$
    – Azuaron
    Oct 30, 2016 at 12:51

5 Answers 5


This pushes the limits of plausible. Eliminating magic in the strictest sense for starters. That leaves alien constructs or super-science (often called 'magic' in this neck of the woods). The OP did try to remove alien constructs, but that doesn't seem possible.

The Kaiju could be teramorphic cyborgs (that's monstrous or monster-shaped cyborgs in quasi-medical jargon), but that leaves as an open question who or what made them.

The Kaiju could be giant robots shaped like monsters. This would take care of the issues of their material strength and powered systems as well as their wide range of morphology. Same problem about who made the Kaiju robots. I will leave this as an exercise for the readers and the OP.

The Kaiju could be lifeforms from an alternative universe where the physical laws are different and environmental conditions more than verge on the nuclear-energetic and permitting the evolution of nuclear-powered, particle-beam zapping mouth parts. Gravity is higher there. The Kaiju are composed of exotic, ultrastrong biological materials.They have nuclear metabolisms. Evolution there favours megafauna. For ecological and geographical reasons, their home territory will be most likely a super-continent.

Presumably somebody carelessly left a wormhole open with one mouth under a nearby ocean. The Kaiju sensing pastures greener have ambled through to wreak urban renewal havoc on our world. Basically it's ecological expansion into new territory.

  • 1
    $\begingroup$ the alternate universe idea is actually really cool and probably the only conceivable option where you could technobabble your way around the absurdities and still keep the audiances suspension of disbelief other than rule of cool or magic. The only thing I'm a bit nervous of is the similarities to Pacific Rim $\endgroup$
    – SolidG
    Aug 19, 2016 at 7:42
  • $\begingroup$ Pacific Rim, eh? Sorry I haven't seen it. Friends recommend it highly. I'm sure there must be some way of making it less similar. Say, a temporary rift in spacetime opens & a colony of Kaiju are shunted through, then they make their way onto land. They don't need all arrive at once. Perhaps, the Kaiju are convicts sent into exile into another universe. Just brainstorm possibilities, start with the most absurd 7 creep up on what makes real sense. $\endgroup$
    – a4android
    Aug 19, 2016 at 12:54
  • $\begingroup$ @a4android: "Say, a temporary rift in spacetime opens & a colony of Kaiju are shunted through, then they make their way onto land." You just came up with almost exactly the plot of Pacific Rim. $\endgroup$ Aug 19, 2016 at 16:21
  • $\begingroup$ Well I guess there may be a few things I can do to make it unique. First off I was never going to actually call them "Kaiju" they're not mindless forces of destruction, but are the dominate life forms in their universe and possess an other worldly alien intelligence that makes no logical sense to most. $\endgroup$
    – SolidG
    Aug 19, 2016 at 16:41
  • $\begingroup$ @NicolBolas. Rodents! I'll have to try better next time. I'll definitely have to watch PACIFIC RIM to avoid reinventing the wheel. Thanks for the tip-off. $\endgroup$
    – a4android
    Aug 20, 2016 at 2:07

Well, with my own kaijuverse, my kaiju (which I am calling behemoths) are giant biologically engineered creations of a prehistoric extraterrestrial civilization, which made them by modifying local lifeforms, strengthening their bones and muscles until they are able to support their own weight. Several of my creatures are genetic chimeras as well, as they combined features from several organisms into one being.


Glitch in the matrix.

These things are impossible in our reality. They become possible only when reality breaks down. Such stable glitches can manifest in a number of different ways, but a particular interaction between glitch and reality self repair / damage control mechanism can create a phenomenon that our sensory apparatus interprets as a giant creature. The reality repair mechanisms shore things up around the glitch and make it somewhat consistent, even though the rules of physics are inconsistent and don't apply.

If the repair mechanisms intrinsic to our reality are unable to resolve the glitch, only contain it, then there might only be one way to dispel the problem permanently. Merge it with another glitch.

  • $\begingroup$ Merge it with another glitch? I'm no coder, but I don't see how that would repair the glitch....wouldn't that just make one worse glitch out of two glitches? Otherwise, I think this is a really good, creative answer to the OP. $\endgroup$
    – Alendyias
    Feb 15, 2021 at 20:13
  • $\begingroup$ Well the other glitch might also be a kaiju. So they would fight! $\endgroup$
    – Willk
    Feb 15, 2021 at 22:48

Lamarckian evolution of spiritual beings

So, this guy used a setting where ayakashi (Japanese ghosts) exist. Now, and that is completely his idea, not mine, he got them the Lamarckian evolution, not the Darwin's one. Basically, an individual species can evolve. It's a personal evolution where ayakashi get more powerful, grow themselves human-like intellect, learn few tricks up their sleave, get again more powerful, etc. For boosting, add inter-species cannibalism, ayakashi eat other ayakashi.

Now, for certain factors (such as presence of ghost/demon slayers) limit the mass evolution to the cap on the surface. But not in the ocean. There is enough food in form of lower-level ayakashi. So, nothing hinders them to grow to excess power levels and (as they are not really limited by physics) excess sizes. You got you your kajus!

Now, let's check your criteria.

  1. The Kaiju range from 100 to 600 feet tall. -- check, they can grow as large as the f... they want and/or can sustain;
  2. They have no set morphology and come in varying shapes and sizes, as a group appearing to be comprised of creatures that vaguely resemble monstrous fish, reptiles, and even mammals and birds. -- yep, ghosts with some kind of initial prototype, but easily changed to fit the purpose;
  3. The Kaiju's skeletons are light weight but are stronger than any metal known to man. -- somewhat, nobody knows what's inside, as they are not fully physical;
  4. Each Kaiju is powered by an integral organic nuclear engine. -- just plain no, unless you count magic as nuclear engine; but hey! It's possible to rationally explain magic... somewhat;
  5. Most Kaiju can fire a particle beam from their mouths. -- some kind of a distant attack seems reasonable for the eternal fight of ayakashi for survival, so why not?
  6. The Kaiju hide is super tough and resilient. -- they are not fully physical, so might well be.

A nice bonus (again, not mine) is a "Kaiju link": if someone/something strong enough gets close enough to the ocean to lure something large from inside, that very being might lure up something even bigger, and so on -- the "bigger fish" style -- up to a Kaiju. That's why they surface up!


What I recommend is that you search information about the largest creatures that have inhabited the earth, especially the sauropods.

Use that knowledge and adapt it to your kaijus

Hope it helps.

  • $\begingroup$ Welcome to Worldbuilding.SE! We're glad you could join us! When you have a moment, please click here to learn more about our culture and take our tour. While this is technically an answer, it's more of a glorified comment. we generally prefer answers that more thoroughly explain themselves. An example of selecting one dinosaur and explaining the modifications would help. Thanks! $\endgroup$
    – JBH
    May 6, 2019 at 22:36

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