Legends of the Rising Sun is a collection of special rules and unit lists for using Legends of the Old West/Lord of the Rings rules for samurai. From Wargames Illustrated 278. Direct PDF download of Legends of the Rising Sun.
Seven Samurai Skirmish is a set of free wargames rules for battles in the spirit of the classic Kurosawa movie Seven Samurai.
An Honorable Victory is a set of free wargames rules for battles set in Japan’s 15th and 16th century clan wars. The author writes:
An Honourable Victory! are an abstract (but not too abstract) set of rules designed for the table-top wargaming of the Clan Wars of Japan during the 15th and 16th centuries.
After one or two games you’ll have them down pat.
The Satsuma Rebellion of Japan of 1877 was the inspiration for the Tom Cruise movie The Last Samurai. Warpspawn has a two player card game set in the period. Like all Warpspawn games, you need to create your own cards and pieces to play. Satsuma Rebellion game.