Based on the biography Miyamoto Musashi: A Life in Arms | Part 1: Beginnings
A Life in Arms reveals aspects of Musashi's life that have hitherto been shrouded in mystery: the source of his deeply troubled relationship with his father, his whereabouts during the Battle of Sekigahara, his unheralded heroism in the summer siege of Osaka castle, and his adventures over the years that followed. We learn of the hidden anger that impelled him to kill his first opponent in duel at age twelve, his single-minded destruction of the reigning Yoshioka sword clan, and his meticulously orchestrated showdown with the great Sasaki Kojirō on Ganryū Island.
Musashi surpassed his teachers and peers to create a school of swordsmanship unprecedented in Japanese martial history, the art of fighting with two swords: Niten Ichi-ryū. Yet throughout his life a yearning for respect was overshadowed by his disdain of authority; an attraction to the mayhem of battle competed with a joy in the contemplation of beauty; and a ceaseless quest for perfection in his art denied him the emotional ties for which he longed. The complex portrait of Musashi that emerges here is a far cry from the one-dimensional caricature in film and folklore.