#Foreword

Hello. I am Shellman.

I first learned about TRPGs as a child, through a play-report article I happened to read in a game magazine. At the time, I did not really understand exactly what kind of game it was, but the image of people gathering in one place and making a story with rules and dice stayed with me for a strangely long time. Later, in middle school, I came across a D&D rulebook by chance and entered TRPGs through the internet. The hobby that began that way has continued to this day.

There are many rule systems I have loved. I especially like GURPS, Pathfinder 1st Edition, inSANe, Beyond the Wall, and Nechronica: The Long Long Sequel. Above all, I loved the feeling that GURPS and Nechronica gave me: building my own character piece by piece. Numbers, traits, and equipment did not feel like a simple list. They felt like parts that showed "how this character fights, how they break, and how they survive."

I also enjoy making original material and homebrew for RPGs. There is certainly joy in using existing rules as written, but I think one of the great charms of TRPGs is the freedom to modify rules and data according to your own taste and needs. Adjusting classes for a campaign, making equipment, adding factions, and writing new rules for scenes that did not originally exist have always been as enjoyable to me as play itself.

The strongest influence on Konsei Reiyotan was the combat system of Nechronica: The Long Long Sequel. I have long loved the feel of reducing counts, activating the maneuvers each character has equipped, and exchanging offense and defense inside a short breath. I wanted to bring into this rule set that strategic tension: blades crossing between range and breath, and the state of battle overturning in a very brief instant.

Another major spark was a campaign I ran with Beyond the Wall. I once adapted that OSR rule set, originally built for medieval European-style fantasy, into a medieval Japanese mood, and I liked both the process and the atmosphere very much. I was also struck by the feeling of making characters quickly with simple numbers, then moving carefully along a boundary where death was always possible. That experience sparked a desire to someday recreate that kind of atmosphere in my own way.

Personally, I have long loved Japanese yoma stories, exorcist tales, and swordsman fiction. Works that left a strong impression on me include Inuyasha, Vagabond, Blade of the Immortal, Ryoko Yakushiji's Strange Case Files, Onmyoji, the Hyakki Yagyo series by Natsuhiko Kyogoku and Ichiko Ima, The Garden of Sinners, and Shinsengumi Keppuroku. I cannot presume professional expertise in medieval Japan. Even so, I tried to place into this rule set as much as I could of the scent of the works I have loved, the strangeness of yoma tales, the tension of sword drama, and the dark romance of an age of war.

There is another reason I chose the Sengoku age as the background. I like the feel of war and unit command found in series such as Total War. Because of that, I wanted this rule set to handle not only the adventure of a single person, but also battles where you hold the Front Zone and lead squads. I thought the Sengoku age was a good background for bringing together a person's blade, the name of a house, yoma ghost stories, and battlefield squads in one place. I spent quite a long time thinking about how to express that through rules.

In truth, the idea of a squad-combat rule set inspired by Nechronica's combat system and set against a medieval Japan x yoma background had been in my head for a long time. This time, with help from generative AI, I was able to give that idea concrete form as documents, rules, and data. The image generation process used the GPT Image 2 model. Claude Code and Codex were used for the Japanese and English translations. This material is an experiment in my own tastes. For that reason, even from the first public version, I included several supporting materials that I felt I needed or had someday wanted to try.

Of course, I understand that there may be resistance or dissatisfaction about using AI to make RPG rules. I do not take that lightly. For that reason, I do not intend to profit commercially from this material or to claim excessive creative rights over results made with AI assistance. I am simply curious how this rule set, made by tying together a system I devised and a background I love according to my own tastes, will look in other people's eyes.

For me, TRPGs are not merely games that end when play ends. They are closer to the act of gathering with people who fit well together, discussing what kind of story to tell, sharing opinions, laughing and worrying together, and creating a single experience. They are also a form of play that includes the memories people keep talking about after the session ends: "that scene was good."

I would be happy if Konsei Reiyotan could take a place among those memories at someone's table. It surely has many shortcomings, but please read it and use it freely. I will always be waiting for generous use and candid feedback.

April 27, 2026

Shellman