Samurai III: Duel at Ganryu Island (1956)

The payoff. Musashi has turned his back on fame and settled in a village, and Mifune plays this older, quieter man with a calm that would be unthinkable in the first film. Everything builds toward the famous duel with Kojiro on the beach of Ganryu Island, where Musashi uses the sun against his opponent, as the legend says he did. It is one of the great swordfight finales in Japanese cinema, and it only lands fully if you have watched the man change across all three films.