From the Introduction:
GENPEI is an unofficial supplement to Green Knight Publishing's critically acclaimed roleplaying game, King Arthur Pendragon, which will allow you to explore one of Japan's most fascinating and captivating periods of history. Founded upon the rules from King Arthur Pendragon, GENPEI's system of Traits and Passions brings your character's dramatic conflicts of honor, duty, and obligation to life. This document does not attempt to reproduce the existing rules in full, and to utilise it you will need either a copy of King Arthur Pendragon or Book of Knights, which features the basic mechanics in an abbreviated and inexpensive alternative to the main rulebook.
GENPEI is set specifically during the period leading up to and immediately following the great civil war from 1180 to 1185.
King Arthur Pendragon and Book of Knights are copyright terms belonging to Green Knight Publishing. GENPEI is an unofficial gaming supplement written by Ian Young, designed to be used with the King Arthur Pendragon game system. No infringement on the copyright of either King Arthur Pendragon or Book of Knights is intended, and no profits are sought from the dissemination of this publication.