http://therovingroninreport.blogspot.jp/2012/04/miyamoto-musashi-festival-duel-at.html
During Golden Week (May 3-5) a small festival is held in honor of the epic duel fought between the legendary swordsmen Miyamoto Musashi (author of the Book of Five Rings) and Sasaki Kojiro known as the Demon of the West. They met in 1612 on the island which is now known as Ganryujima and when the duel was over Kojiro lay dead and Musashi was victorious.

The actual details of the duel are debatable but the legends of it are very persistent. It's said that Musashi purposely arrived late, unwashed, and carrying a wooden sword he had carved out of an oar on the way over - all of this to unnerve his opponent. Kojiro is said to have struck first but failed to cut Musashi down. Musashi smacked Kojiro on the head killing him or in the some versions finishing him off with a blow to the ribs.