From the back cover:
DISCOVER WHAT FOUL CREATURE HUNTS FOR NEZUMI BLOOD IN THE SHADOWLANDS
As a band of samurai travels through the dangerous, twisting landscape of the Shadowlands they encounter strange rat-like creatures called nezumi. The scouts describe a monster who hunts their tribe and they plead with the samurai for aid. Faced with a possible lead on their adventure, the samurai must choose whether they will help or destroy the scouts of the Knotted Tails tribe.
A supplemental storyline for Mask of the Oni, The Knotted Tails expands upon the information presented in Shadowlands, a sourcebook on the twisted machinations of the fallen Kami Fu Leng and introduces players to a remorseful tribe of nezumi. This storyline for the Legend of the Five Rings Roleplaying Game offers heroes a mystery to solve and a slight reprieve from the the dangers of the Shadowlands while they journey onward towards Shiro Hiruma.