Musashi founded his own sword school, the Niten Ichi-Ryu, 'Two Heavens As One School', after his style of fighting using both the samurai swords as one weapon.
He taught hundreds of students over the years, but it is said that at the time of his death not one of Musashi's students could master his devastating technique and the style died with its creator.
Watch this video which shows what the school in the book may have looked like:
Mount Shosha (書写山, Shoshazan) is the site of Engyoji (円教寺, Engyōji), an atmospheric temple complex with a history of over 1000 years, located at the edge of Himeji City.