Shinobi Ryu is the companion book the the criticlly acclaimed Shinobi: Shadows of Nihon sourcebook (also available on this site).
The book includes a detailed history and description of a number of historical shinobi (aka "ninja") ryu or clans, NPC write-ups, and a sample shinobi village.
Shinobi Ryu contains additional information for both GMs and players,... [click here for more]