Kurotokage Cthonians
edogawa.jpg This article was created with material from the abandoned Kurotokage sourcebook project. That material is in the public domain since 2003. The unfinished original content is archived.


  • Overview of Japanese deep structure or, Geology of Japan for Beginners. Includes:
    1. Japanese subduction zone (presented as a hands-on info file from the 1958 DG Operation: AHAB)
    2. A 1958 geological report about the trail of the cthonians
    3. A more recent report about geological anomalies in Japan
    4. Brief glossary/tech sidebar
  • Cthonian ecology - or why they like it under Nihon. Includes:
    1. Cthonian timeline and general bio overview (keeper's eyes only)
    2. Why Cthonians love it down there & the Cthonian way of Life (more Op: AHAB, Kurotokage and Taininhodo docs)
    3. The diary of a lone Tokugawa-era yamabushi that somehow connected with a cthonian and witnessed part of the burrower's social life
    4. Field notes from a Meiji-era insect collector witnessing the hatching of a cthonian egg and following the earlier stages of a cthonian's life
    5. A manga script and explanatory letter from a notoriously deranged mangaka (submitted to a publisher but 'lost' after a B&E) full of hentai tentacle sex and hints at cthonian sexuality (hentai as effect of cthonian libido seepage).
  • The Cthonians and the Japanese. All the rest:
    1. How Zhang Daoling trapped a Cthonian under <insert opportune location> (maybe two or three versions of the same tale, with varying Mythos elements, and varying tie-ins with other chapters of the book)
    2. Cthonians & CATFISH (a collection of docs recovered and compiled by Kurotokage operatives or Anti-Mythos Monks through the years)
  • Possible expansions/sidebars/stuff….
    1. Japanese Civil Protection details and DG-style template NPCs (who knows…. a Cthonian yamabushi cultist, a non-conformist geologist keeping up Mogi's research, an oversensitive manga artist etc)
    2. New Cthonian Spells/Abilities - Mating Call, Clan Summoning etc.
    3. Keeper's Help - some new and alternative takes on the old 'stolen cthonian egg' scenario seed.

Section 3: Trail of the Cthonians

All I have at the moment is a reference to K. Mori's article from 1964 in a book by geological maverick Forese Carlo Wezel, and a map from the K. Taira 1964 companion work.

In the '50s, Benioff postulates that earthquakes are not random events, but the expression of a global system. With the forthcoming International Geophysical Year and all that, a lot of work gets done and a lot of data get collected. Following up on Benioff's models, Japanese seismologist K. Mogi starts an in-depth historical study of seismic events in the Pacific Rim. In 1964, together with K. Taira, he compiles and plots data for the period between 1930 and 1964. The result is Taira's Map. The map shows three distinct trails, each marked by an alignment of successive seismic events. That is, each trail is made of the points representing a recorded earthquake. [you'll probably need a map or atlas to follow this, but believe me, it's worth it].

The First Track starts in Krakatoa, in the strait between Java and Sumatra in 1940. It follows the western coast of Sumatra and, curving slightly by the Andaman Islands, enters the Gulf of Bengal and hits the Asian continent somewhere north of Rangoon in 1950. From here on it marches with a path slightly curving eastwards, and enters China; the track follows the southeastern border of the Kunlun mountains and reaches the Nashan region, to disappear in 1957 somewhere between Nashan and Mongolia.

The Second Track starts in the Banda Sea region in 1940, points northwest to hit Mindanao and Leyte in the Philippines and then goes on due north, past Taiwan and up to the stretch of sea in front of Shanghai, just south of the tip of Korea (Quelpart island). Here the trail deviates sharply to the northeast, passes along the pacific coast of Kyushu on a curved path leading it to hit the Tokyo region in 1950. From here it continues northeast-wards along the Honshu and Hokkaido coast, follows the Kuriles and in 1960, a few hundred miles from Kamchatka does a sharp eastwards turn, crosses the Pacific in an almost straight course and hits Alaska in 1964.

The Third Track starts off the coast of Guatemala somewhere in the '30s. It follows the isthmus due east and then turns sharply south by Malpelo Island, hitting Ecuador and Peru in 1940. From here it runs along the eastern side of the Andes till it reaches Bolivia, where it does a sharp turn to the southwest, hits Chile just south of La Paz in 1950 and then follows the Chilean coast due south reaching somewhere south of Santiago in 1964.

Note that:

  1. All tracks are practically smack on the equator in 1940, while they are all in subpolar/peripolar zones by 1964 (we can extrapolate the trend of the First Track from the data at hand).
  2. All tracks weave through the 'Fire Ring' margin instead of following a parallel to it.
  3. All tracks are defined by ipocenters (that is, the deep seats of the energy release we perceive as an earthquake) at around 100 kms of depth.
  4. As a bonus, Globally earthquake energy releases grow steadily between 1930 and 1960. To be blunt, quakes get nastier over a period of thirty years all over the world

Section 4: Cthonian ecology - or why they like it under Nihon

Cthonians travel in clans or extended families. Shudde M'ell being sometimes described as 'Sultan' of the Cthonians hints at a patriarchal structure, in which a single alpha male is granted the attendance of a number of females and submissive youngs in various states of development. This one also ties in rather well with the fact that the strongest and best known Cthonian spell (the one that causes a focalized earthquake) is described in the CoC books as a group spell. I just wonder if the required group is the single clan or if it is something like a Council of Clan Heads. Both possibilities have their pros and cons.

Cthonians are a migrant species, each clan following certain defined paths in the planet's mantle. Migratory paths seem to skirt the vast oceanic plates, and stick to consumption margins (where probably the geochemistry of the environment is more suited to their needs). In particular, I think that water - which we know can be lethal to Cthonians in vast quantities - is still a needed component of the optimal cthonian living environment - and the only place to find water in the mantle is in Benioff zones.

(factual) thermal anomalies postulated in the sector of crust and mantle underlying Japan make the area particularly agreeable with the cthonian reproductive cycle.

The idea is that the mantle under Japan - at something like 100 kms depth - couples the high temperature of a much deeper setting with the water content and low pressure of a superficial setting. The equivalent of a cool, sunny day with a slight breeze, for cthonians.

A more stringent evolutionary problem might well be part of the cthonian predilection for Japan's Benioff zone. To wit….. the Cthonian egg is a relatively small geodes-like object, containing a miniature cthonian that, at this stage, can be severely damaged by a small flame; in technical terms, instar-class cthonians (young adults and adults) need high temperature and pressure to survive, while the cthonian hatchling needs surface conditions.

I here rewrite the bit about 'Cthonian Life Cycle' bit n the CoC rulesbook.

The 'geodes' is a protective capsule for the cthonian embryo, shielding it from much temperature and pressure, while acting as a permeable membrane to extract the necessary (light) elements from the surrounding magma.

Hatching of the geodes is caused by two events

  • full development of the embryo
  • drop of temperature and pressure to surface-levels

This could be an evolutionary strategy - if, as I imagine, after coupling the cthonian female equivalent produces a few millions of cthonian eggs immediately after coupling (or during coupling), the cthonian ecosystem needs a mechanism to weed out the excess.

Laying eggs in an upwelling of magma is a way to ensure selection: those lucky enough to complete their development and reach the surface thanks to volcanic effusion are 'winners' and survive. The others either develop but remain in the magmathic chamber (were they are baked by the heat) or (less likely) they reach the surface too early and lack the elements needed to achieve full development.

[OK, so it's all a matter of luck. But cthonians are clearly high-POW and therefore high-Luck critters. Any strategy weeding out the losers is good evolution for them]

Magmathic chambers under the Japanese archipelago are the ideal egg-laying chambers, that can couple at leisure in the relatively shallow depths under Japan and then trust their not-yet-born offspring to upwelling melted rock 'bubbles', that will carry the survivors in the magmathic chambers, for the first phase of development to take place, waiting for the next eruption.

By coupling the closer they can to the surface and by using vast chambers of fluid magma under active, frequently erupting volcanoes, as 'incubators', the cthonian parents can try and give a minimum of edge to their young.

Final consideration, once fully developed, cthonian babies start the long dig down towards home. They get adopted by the first clan they meet (thus ensuring genetic pool variety).

This said, we come to the lowdown and dirty part of this. Cthonian coupling. My current rough ideas, waiting for the full Hentai treatment, are

a . cthonians do not have a sexual characterization before coupling

b . the coupling is preceded by a fight that culminates in the winner raping the loser and turning it into a female (this grants us the right harmonics of sex and violence to send all oversensitive Japanese mangamaniacs abuzz with hentai visions)

c . 'mating' is therefore both a way to keep the line going and to determine the clan leadership

d . the cthonian female lays eggs only once in its life cycle, and after that spends the rest of her existence educating the young and burrowing through the mantle. Females have no decisional power and probably lose their original intelligence, therefore the idea of turning into a female is particularly dreaded by still sexless cthonians.

e . when the new kid in town defeats the old sultan, the sultan gives birth (with predictable terrific spasms and the obvious ancillary surface devastations) and dies with a Cthulhu-class psychic backlash.

I've further refined (?) my angle on cthonian sexuality, trying to make it more relevant to a model of cthonian society and politics. Let's see if you like this one….

Young cthonians are sterile hermaphrodites. When they reach the proper age (or when they feel like - more about this later) they challenge the clan head to achieve control and (as a thrown in bonus) sexual identity and activity.

a . if the old leader wins, he rapes the loser that gives birth and from there on is a sterile female nurse

b . if the newcomer wins, the clan head dies (so we eliminate completely his genetic input from the pool) and the winner has power and male status. But he has at this point to wait for the new challenge to actually produce offspring.

Point b, with its death of the elder and no offspring generated adds some spice to the stew. Should the new leader be in his turn defeated by a newcomer, we again get no offspring. It's easy to see the underlying message - a weak leadership means a demographic depletion, hence damage the whole race (as clans grow by adoption, reducing the number of available youngs damages everyone). The head of the clan has therefore a racial imperative for being strong and ruthless.

See, we started with two giant magma-squids making out in the mantle and now we have some snippet of cthonian culture.

Let's complicate matters.

I said 'if he feels like'.

A cthonian of the right age can decide to avoid challenge, remaining attached to the clan as a sort of ermaphrodite eunuch. These could be the preservers of the racial lore, and/or the soldiers of the clan (probably they've a load of sexual frustration to discharge). Also, for a certain period (let's say till they get into third instar) they can change their mind and challenge the leader.

So we get this clan social ladder

1 - the clan head

2 - the older, 'stable' eunuchs

3 - the eunuchs still capable of challenging the boss

4 - the young, untested ermaphrodites

5 - the female harem

This gives us a certain political character for the clan. The young eunuch and the leader are keeping an eye on each other, wondering when the right time will come, if ever. For the eunuch, the best time to try his luck is just after a succession fight, hoping to catch either the

old leader or the young newcomer tired after the exertion .

What gives?

Well, I picture old Shudde M'ell as your classic backstabbing bastard, that laid low when it was time, nurtured a young hopeful as a tool to weaken the original leader of his clan, and then stepped in, assumed power, rose to dominance in the council of clans and ultimately attained godhood.

Pretty Japanese, all things considered.

And if the whole reminds you of what's been happening above-surface in the last few centuries, well, maybe there's some truth about the stories of cthonian psychic leakage. After all, there's power, and not just tentacle sex, in the cthonians minds as they copulate. And someone's bound to pick it up.

Imagine the Cosmic Irony (TM) - the most ambitious conspiracy in the history of Japan (and quite possibly humanity) is just a reworking of some weird giant underground squid political bickerings.

NOTE - I'm for not spelling this last 'Cosmic Irony' out in the sourcebook. Just hint at it and let wicked keepers pick up the joke.

A fate worse than death…. I see your point, but as you see I'm trying to make every little bit I threw in useful for defining better the cthonians.

Now I'll have to flesh out the above (input welcome) and try and find something useful to say about the council of clans.

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