Sengoku Chanbara Roleplaying in Feudal Japan Revised Edition

From the introduction:

Sengoku is a roleplaying game for one Game Master (GM) and anywhere from one to 180,000 players (assuming you want to play the Battle of Sekigahara on a 1:1 scale). Sengoku is also a word meaning "Warring States," and refers to a period of Japanese history marked by nearly incessant civil warfare, jockeying for position by rival warlords and samurai clans, and a near total breakdown of the social order.

User summary:

See also Sengoku Diceless