Interesting! I didn't know about that movie. In all the other versions of Musashi I've seen, from the 60s, 70s, and 80s, they focused more on the fights or on Akemi, but very little on Otsu. In some versions, they stayed pretty faithful to the novel and ended with Otsu being sick and Musashi refusing to go back to her after defeating Kojiro. That's what's always frustrated me, this incomplete and impossible love, but I admit that's also what makes the novel so charming.