Bushido meets Call of Cthulhu

Well, that's my pitch. And it's a good one.

Cover art is 'Female Human Samurai' by Sly Tiger Art Studio artist S. Farebrother
​You can find the rules on drivethrurpg or Amazon

A few months ago I brought out the classic RPG Bushido and started running trial games. Bushido is one of those RPGs I owned in my callow youth, but never got to play. It gathered dust on the shelf, taunting me from afar. 2025 was the year to settle my account with FGU's famously impenetrable game. 

It's a classic, but my Maths brain is now mush

I wrote about my experience with Bushido on a previous blog. Long story short, there's been a reversal. Back when I was 15, me and my nerd friends weren't at all daunted by Mathematics; it was the cultural strangeness of Bushido that frightened us off. I couldn't think of any stories to GM in such a setting; the one published scenario (Valley of the Mists) was impenetrable. My players baulked at roleplaying inexplicable characters like Yakuza gangsters and Gakusho priests. This would have been 1982. My mum had watched the TV series of Shōgun with Richard Chamberlain - and that was as far as anyone's awareness of feudal Japan went, at least in my postcode.

Now, we're forty years later. There's been a new TV series of Shōgun with Hiroyuki Sanada and Anna Sawai. I'm pretty au fait with all things Oriental, as are my gaming buddies. No one would bat an eye at roleplaying a Yakuza or a Ninja or a Ronin warrior. It's the Mathematics that frightens us.

Bushido is a bit of a bookkeeping burden. Combat is fine: it's just D&D with extra steps. The magic system is OK (although uninspiring). The system for studying skills or building gimmicks is delightful. But the numbers overwhelm. Creating a character involves numbers trickling down from core stats to derivative skills and abilities in a way that makes me marvel how people did this in the days before Excel spreadsheets. Once your character starts gaining experience and honour, studying, and training, it all gets a bit out of hand. But in a very slow, ponderous way, since Bushido​ doesn't want you to get anywhere too quickly.

 All of which is to say, I ended up writing my own Bushido rules using the D&D-derived 'Hack' system I love so much. Here it is: the Yōkai Hack.

I started the project under the working title 'The Bushido Hack and my intention was pretty simple: adapt the D&D-inflected Black Hack rules to cover Feudal Japanese combat conventions and Japanese-themed magic, then develop some granular rules for training and research to capture that distinctive aspect of Bushido. I thought it would be a throwaway sort of product between more serious ventures.

​But it turned into another consuming obsession.

It also took on its own tone and direction. Perhaps it was the cover illustration I sourced from Sly Tiger Art Studio - did you look carefully? The lady Samurai looks terrified, surrounded by shadows, strange mist roiling around her, her hand on her katana seems to tremble. It looks like the cover of a horror story.

This is what brought the Yōkai to the fore and gave the game its new name.

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What's a Yōkai ? And why do we care ?

'Yōkai' are magical critters in Japanese folklore - the word covers phenomenon as varied as poltergeists and cursed objects through to faeries, ghosts, and demons.

Yōkai is a word that doesn't feature in Bushido, which prefers the dull term 'Supernatural Beings' instead (Bushido is written in a wargaming rules style that is positively allergic to romance).

Bushido seems to be distinctly ambivalent about the supernatural. Yes, there's magic, cast by Gakusho priests and Shugenja sorcerers, but it's all small scale stuff, nothing that transforms the feudal setting or disrupts the historical plausibility. The Supernatural Beings are low key entities. Bushido seems to want you to play a game revolving around politics, feuds, military action, and crises of duty, with a few monsters and spells thrown in to make the transition from D&D a bit less jarring. 

Tengu Samurai by Jacob E. Blackmon - the sort of antagonists that Bushido seemed to downplay

I didn't want that. I wanted PCs to be courtiers and entertainers and fortune-tellers and exorcists, people with lots of social skills but very little to offer in a combat situation, who could still negotiate an adventure.

That's why the Yōkai loom larger in my game. I wanted a more apocalyptic setting, where the political turmoil of the pre-Edo world is mirrored by an invasion of supernatural monsters - the Yōkai - who can impersonate people and spread corrupting Pollution by their very presence.

Immediately, the game takes on a detective theme. In many scenarios, the insidious spread of Pollution is the problem. There are gateways to the Yomi World that must be sealed. There are cursed items that must be cleansed. There are supernatural intruders who must be exposed and driven out, dispelled, destroyed, or exorcised. You can't do all of that with swords and ninja flash-bombs.

Of course, you can, in you prefer, play the Yōkai Hack with a Bushido-sensibility: downplay the supernatural, focus on court intrigue, duels, and skirmishes. The game allows you to do that. But I've written it to be more like Call of Cthulhu in feudal Japan, with the Pollution replacing Sanity. 

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What's In The Book

At 240 pages,  The Yōkai Hack is by FAR the biggest of my Hack-RPG books.

Why so big? The Skills and Spells take up space, but it's not just that. There's a much more expansive treatment of combat, taking the light and frothy Hack-rules about as far as they can go in the direction of granular, tactical decision making without abandoning the Old School sensibility entirely. Then there's the consideration of the setting, culture, religion, technology, all of which needs exploring. Finally, I wanted lots of tables to generate encounters, NPCs, and whole stories randomly.

Character Classes

Much will be familiar to anyone who knows Bushido or Oriental Adventures (the 1e AD&D expansion). Of course you can be a Bushi warrior, a Yakuza rogue, a Shinobe assassin, or a Sohei warrior monk. The Taoshi martial artists have a made-up name but inhabit a recognisable archetype. Majutsushi are elementalist sorcerers.

Other character classes required me to be more creative. Geinōsha are entertainers, which includes classic geisha but also poets, actors, clowns, and artists. Onmyōji are magic-users focused on prophecy and omens. Reishō are diplomats and negotiators, anything from a slick courtier to a gangster extorter, they excel at making deals. 

​Seishinban are entirely made-up for this setting: spirit-wardens and exorcists whose focus is squarely on exposing the Yōkai and cleansing Polluted people and places.

Vengeful Geisha by Bradley K McDevitt

These character classes have ways of dealing with many problems that don't involve swordplay. Geinōsha  can extract favours from someone who sees them perform (whether that performance be a song or poem, the creation of beautiful calligraphy, or an exquisite tea ceremony). Reishō ​can lie irresistibly. Even Yakuza can design their body tattoos to give themselves a bespoke set of abilities.

Tests & Usage Dice

Like standard Hack-RPGs, most tests are done by trying to rollunder your Stat (STR, DEX, CON, WIS, INT, CHA, the old gang) on a d20. Level differentials give you a bonus or a penalty, making it difficult to succeed against high-Level NPCs or high-HD monsters.

The real innovation of the Black Hack was the Usage Die. This is a die representing a resource of some sort (arrows, energy, magical power). When you roll it, it shrinks to a smaller die if the highest two numbers come up. The original Black Hack had the die shrinking if you rolled 1-2, but there are various good reasons to make the shrink happen when the highest two numbers come up.

My various Hack-RPGs really lean into this mechanic, since Paul Baldowski’s The Cthulhu Hack opened my eyes to just how far you could take it. In Yōkai Hack, Honour is a Usage Die. When you put your Honour on the line (to demand respect or a favour), you roll it to see if it shrinks; likewise, dishonourable behaviour forces you to roll it too. Instead of keeping track of money, you roll your Wealth Usage Die, which might shrink after the purchase. Ki, that mysterious Inner Power, can be tracked as a Usage Die too.

Pollution is a bit different, because it's a Usage Die gets BIGGER instead of shrinking. Each increase in size triggers an episode of derangement, bring your corrupted personality to the fore. When it balloons past D20 size, your Utter Calamity befalls, a tragic doom overtakes your character, from which there is no coming back. I encourage players to choose (or roll) their Utter Calamity right at the start of play, so they can bring a bit of foreshadowing into their roleplaying.

Training & Study

One of the signature tropes of Bushido and the wider 'feudal Japan' setting is the focus on skills and training. It can't just be about going up Levels and getting more powers. Players in this sort of game want and deserve more agency than that. But squaring the circle of skill-progression and level-progression is something that has bedevilled D&D for a long time.

Here's what I came up with.​

You pick a skill or magical spell or Stat increase that you are working on. The GM gives you a Usage Die for your training. You roll this Study Die between adventures and at certain points during a scenario, such as during a 'training montage' or a moment of insight. Once the Study Die has shrunk away to nothing, congratulations: you have learned your skill or spell.

Then you choose your next skill/spell/Stat and get a Study Die for that, but the catch is, it's always starts off a size bigger than the last one. This means each skill or spell becomes more laborious to acquire.

Going up a Level is great, because it resets your Study Die to a smaller size.

This simple system is festooned with variations. Some characters get more 'study periods' between adventures and others get more 'study points' during adventures. Some skills are difficult, automatically increasing the size of your Study Die when you set out to acquire them. Having great teachers or teaching scrolls lets you roll extra times.

Every time your Study Die shrinks, Duty comes calling. Each character has a Duty towards some person or group and they have tasks for you that are certainly inconvenient, sometimes dangerous, occasionally lucrative. Each character builds their own 'Duty Table' from elements taken from their Character Class and Social Superior. Neat!

Create Your Own Poetry!

I include the normal milestone-based Levelling system for a Hack-RPG, but also an optional system based on discovering the meaning of your own personal poem!

In the appendix, there's a bunch of tables of words culled from Japanese haiku. You can roll your own 3 word line as a 1st level character. 

​The pale butterfly lingers

Or how about:

Grief softly dances

You level up once you can explain the meaning of your poem to the GM and how it relates to something meaningful to your character that happened in the scenario. Then, at 2nd level, you get a 4-word poem, such as:

The chrysanthemum dreams of the ancient garden

Longer lines might take more scenarios to interpret, but eventually you will have a multi-line poem describing your PC's adventures in a beautifully cryptic way.

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Cultural Considerations

I know you cannot win with this, but I'll do my best.

Look, I'm not Japanese. I'm not a scholar of Japanese. I've not even been to Japan. I'm conscious of the critiques of 'West-splaining' and 'Orientalising' Japanese culture and history. But hear me out!

I'm not trying to write a game about Japanese history or society, just one set in a fantasy world that draws on archetypal themes in Japanese media and mythology. To that end, I don't identify the setting as Japan: it's just 'the Archipelago.' There are no real-world states, cities, or rulers mentioned. 

Buddhism isn't mentioned, but there are monasteries devoted to the Lotus Path and its Sages. I steer clear of Shintō, but include the Torii Path of shrines and spirits. I agonised for a while over Kami, those gods and demi-gods of nature. They are real objects of veneration in real religious practice. But I figure the term has also crossed over into general usage in the fantasy genre, like 'angel' or 'faerie' or 'djinn.' I came up with new names for the Kami of the Archipelago to avoid appropriating Amaterasu or other real-world divinities. 

GMs and players who bring the game to the table can make their own peace with these issues. I suspect most people are going to call Buddhism 'Buddhism' and the Heavenly Mountain 'Fuji' and call the Archipelago 'Japan' or (as Bushido​ does) 'Nippon.' 

One area that occasioned me reflection was the 'outcaste' group that spawns the ninja subculture. Bushido terms this caste 'Eta' - a term I learn means 'filth' but perhaps derives from animal feeding - whereas the modern term is 'Burakumin.' Their status is still a political concern in Japan. There is a Buraku Liberation League. This isn't material to be carelessly handled.

Nevertheless, players of Japanese-themed fantasy RPGs want their ninjas - and rightly so - and ninjas need to come from some sort of outcaste community. My solution is just to name the outcaste subculture 'Tsumi,' a name hinting at sin or misfortune and describing a caste that does work that is ritually Polluting (butchery, tanning, handling corpses). 

Ninja Throwing Star from JE Stock Art

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Where Does  Yōkai Hack Go Next?

There's already an introductory scenario available: The Bride With Two Faces. It's free to download from drivethrurpg and sold at-cost on Amazon.

The Bride With Two Faces takes its plot from Beneath An Opal Moon.

I needed a quick scenario to playtest The Yōkai Hack and was reminded on Beneath An Opal Moon, which is a great little scenario in just a dozen pages, created by Mongoose Publishing for their Samurai of Legend RPG.

SAMURAI OF LEGEND

Samurai of Legend is an Open Content RPG that explores an early period in Feudal Japan with admirable focus: the rise of the Samurai class that the weaponised Buddhism that came to define them. It uses a version of the Runequest/Basic Roleplaying system, which suits Samurai pretty well. Beneath An Open Moon is likewise Open Content, and invites readers "to reproduce this text and build upon it with your own scenarios and mechanics," adding: "You can even print and sell such work, if that is your desire (and we would wish you the very best of luck if you choose to do this!)."

I rewrote most of the text and added more political layers to the plot, as well as encounter tables, stat blocks, and suggested magic items for dealing with the demonic Yōkai that are the root of the problem.

I think that, even if you prefer Samurai of Legend to The Yōkai Hack, you will still appreciate the expansion of this scenario.

I'm putting together a setting book, for a coastal city, its Daimyo and clan politics, and the local Yōkai nemesis, and a few plot threads that tie them all together.

If you enjoy The Yōkai Hack then I'll enjoy your feedback.