This is one of the 'Sengoku Gunyu Den' series by Tsukuda. This series is a operational warfare in Japanese Warring States era (Sengoku-Jidai). This particular game is on the Motonari Mori's earlier battles. Mori clan was the victor in the western most part of Japan. Thus Mori clan was called as 'Saigoku no Yu (Champion of the West)'. The title was taken from this.This game is based on the Battle of Itsukushima which pitted 4,000 men from the Mori clan vs. 40,000 men and the Mori's won the battle!!!!!!This battle is included in the game. And of course, scenario rule lists HEAVY restrictive special rules to emulate the outcome - BoardGameGeek