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This is a playtest draft of IKEZU-ISHI (Malicious Rock), a feudal Japan inspired hack of Cairn and Into The Odd. This document is a work in progress and will be updated with edits and additional comments. Any comments, suggestions, or feedback are appreciated and can be emailed to serialprizes@gmail.com.

While this supplement is inspired by Japanese mythology and feudal society, it is by no means meant to be a historically accurate text. Citing this in an academic setting will more than likely result in a terrible outcome, but if you want to play Samurai and hunt Yokai in Cairn then you’re in the right place.

Please feel free to treat any information in this book more as a guide than hard and fast rules. Many elements within this book are simply reskins of existing rules or NPCs in Cairn or other supplements for thematic purposes. Just as I have taken some liberties with the historical and mythical accuracy of some stats, you too can adjust any of these elements to fit your needs and game. Just be sure that all players are in agreement on any changes or adjustments before beginning play.

Mar 26, 2024 Update v0.4

78 pages, more than 30 tables, 79 encounters, hexcrawl generation, solo rules, and so much more!


Mar 8, 2024 Update v0.3

Large update including (but not limited to):


  • Narrowed to remove largely duplicate Backgrounds
  • More recommended starting gear for each Background.

Tables for Exploring is now Tables For The Guide and added

  • d10 wilderness encounters
  • d10 Wilderness locations
  • Settlement size, habits and customs
  • Village or settlement events
  • services at an inn or tavern
  • NPC combat tactics
  • d100 NPC Quirks
  • d100 Nouns/Verbs/Adjectives

Solo Play tables added including

  • Yes/No
  • Likelihood
  • Complex Questions
  • Plot Twists

Appendix A: Additional Tables for Character Creation including:

  • Names
  • Complications
  • Attributes

Rules quick reference added

A lot of formatting changes to font, layout, placement of tables, etc.

Feb 13, 2024 Update v0.2:

  • More equipment and rules from Cairn
  • Human, Animal, and Yokai NPCs
  • Tables for exploration in the setting
Updated 23 days ago
StatusIn development
CategoryPhysical game
Rated 5.0 out of 5 stars
(7 total ratings)
AuthorSerial Prizes
GenreRole Playing
Tagscairn, Historical, into-the-odd, japan, OSR, samurai


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Click download now to get access to the following files:

Ikezu-ishi (Playtest V0.4) 802 kB

Development log


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(1 edit) (+1)

Amazing!!! Would be possible to get some kind of Card Character Sheet? I haven't seen many sheets using Feudal Japan theme, it would be nice! Plus I love using cards, I was thinking to print by myself the complete Bestiary in card format to use it.

Thanks! Character sheet is in the works for the next version (as well as some additional cleaning up and stuff) but I'm a big fan of cards and other supplements to help move the game along. Good suggestion, I'll look into it and keep it in mind when putting the character sheet together.


Very much interested in this probably going to use this for some of my solo world building. 

Is their any particular playtest feedback you're looking for currently?

Awesome, I'm hoping there's value in this even for folks who want to worldbuild outside of the game. 

For feedback, any is appreciated, but specifically if the worldbuilding tools are well organized, complete enough, and make sense. Spent a lot of time trying to settle on order of things for flow purposes so want to make sure it all works. Thanks!

(4 edits) (+2)

A piece of linguistic advice, if I may: Choose a single transliteration method and stick to that consistently. As you might be aware, there are several methods for the so-called romanisation of Japanese words. For example, depending on the method, the word 浪人 can be transcribed as rounin (literally), rōnin, ronin or even as rohnin; much like the word 妖怪 can be transcribed as youkai (literally), yōkai, yokai or yohkai as well. Now, once you picked one, whichever it may be, you should apply that one for each and every word, accordingly. For example, if you choose to use the rōnin, ryōshi, kōfu, etc. format, then yatou should be yatō and sougiya should be sōgiya too; and vice versa (speaking of which, among the Human NPC’s, rōnin is ronin instead). Similarly, words like sohei, wako, shakujo or bo should be sōhei / souhei, wakō / wakou, shakujō / shakujou and / bou, respectively. (Well, personally, I would not endorse using letters with macron and/or circumflex diacritics, and highly prefer the literal transliteration instead.)

 Also, some cultural remarks on certain words:

・Bandit (Yatou): yatō / yatou (野盗) does mean bandit or brigand, indeed (literally, “plains robber” or “field thief”), but I would suggest considering sanzoku (山賊) instead.

・Cleric (Shinshoku): shinshoku (神職) is a specific term, referring to Shintō Priesthood; while the Cleric’s weapon, the shakujō (錫杖), is a traditional Buddhist weapon (khakkhara, in Sanskrit). For Cleric, consider using some other words like seishokusha (聖職者), sōryo / souryo (僧侶), shisai (司祭), etc. instead. Note: Since the game is supposed to be set in the Japan’s feudal period (during the 12th to 19th centuries, that is), both religions as well as their various syncretic forms can be relevant.

・Gambler (Bakuchiuchi): bakuchiuchi (博奕打ち) is a professional gambler, expressively. Also, consider some other words like tobakushi (賭博師), etc. instead.

・Herbalist (Kusushi): kusushi (医師 / 薬師) is simply an obsolete word for doctor or healer (including herbal medicine). Also, consider some other words like honzōgakusha / honzougakusha (本草学者), honzōka / honzouka (本草家), kanpōi / kanpoui (漢方医), yakuzaishi (薬剤師), etc. instead.

・Merchant (Shāngrén): shāngrén is the Chinese reading of the word 商人, of which the Japanese reading is shōnin / shounin. Also, consider some other words like gyōsha / gyousha (業者), chōnin / chounin (町人), etc. instead.

・Performer (Sarugaku): sarugaku (猿楽) is a specific term, referring to the Noh Theatre of the Kamakura and Muromachi periods (especially during the 11th to 14th centuries), while the game is supposed to be set in the Japan’s feudal era (during the 12th to 19th centuries, that is). Consider some other words like geinōjin / geinoujin (芸能人), engisha (演技者), etc. instead.

・Servant (Meshitsukai): meshitsukai (召使) does mean servant or menial, indeed; although such words might imply different nuances than their equivalents in certain cultures. Also, consider some other words like shimobe (下部), kerai (家来), etc. instead.

・Undertaker (Sougiya): Although funerals and graves do exist in Japan, Western-style burials employing funeral directors and morticians are relatively modern inventions (compared to the game’s supposed setting). Sougiya (葬儀屋) is a specific term, referring to the latter; which seems to be confirmed by the character’s weapon: a Shovel. I would suggest considering some other words like onbō / onbou (隠亡) [cemetery guard / crematorium worker], hakamori (墓守り) [gravekeeper], hakahori (墓掘り) [gravedigger], etc. instead.

・Tetsu Katana (Iron Sword): This sounds like a weirdly awkward combination of words; plus if you use tekkō (鉄甲) for iron knuckles and tessen (鉄扇) for iron fan, then for iron sword, tekken (鉄剣) would be the most obvious and proper choice.

・Ō-yoroi Armor: ō-yoroi (大鎧) means “great armour” or “big armour”; yoroi (鎧) might suffice in itself.


Please note that I have no intention to criticise or nit-pick here. On the contrary, I would fully understand if you are not interested in such details, but since I do like the basic idea, I just thought I would comment on this particular aspect of it.


Woah dang this is incredible, thank you! These are exactly the kind of details that push the limits of my admittedly mainstream, generic, western based knowledge and that I absolutely want to get right. Definitely taking all of this into account for next edits (coming soon because of formatting issues in v0.4). Certainly feel free to let me know any other things that stand out to you, but may I also reach out for additional input if I have questions? Thank you!


Sure, anytime.


Excellent project! If you need any help, count on me!

Thanks! Expect me to bug you in the near future!