Tokai is Yoshikawas' other book that takes place right before Musashi. Taiko is about the famous generals of the warring states period and focuses on the peasant general Hideyoshi. the books end is the battle of Sekigahara. that is the battle that the Musashi novel begins with. Taiko is a bit closer to historical record while Musashi is written as more of a folk tale. Taiko is a bit dryer (i think its due to translation) but its a great book too.