The Hidden Fortress
This is the big one, the one that gave George Lucas much of the basis for A New Hope’s plot. Akira Kurosawa’s energetic adventure film tells the story of a Japanese general bound to protect a rather self-sufficient and sarcastic princess (and her fortune) after her family is attacked and her home destroyed in the midst of a clan war. The story is told largely from the perspective of a pair of bickering peasants who, after missing the battle they’d planned to fight in, unwittingly stumble upon the general, the princess, and a whole lot of gold.
Lucas has openly acknowledged the debt that A New Hope owes to The Hidden Fortress. The opening of The Hidden Fortress starts with the two peasants Tahei and Matashichi, their constant, comedic insults setting the tone and explaining the backstory before we reach the plot proper. Tahei and Matashichi are the prototypes for R2-D2 and C-3PO, although the latter pair are a bit more altruistic in their goals.
But the parallels do not stop there: Princess Yuki, self-centered and sarcastic even in the midst of great danger, reads as the basis for the equally independent Princess Leia, while her protector General Rokurota is Han Solo, Luke Skywalker, and a touch of Obi-Wan rolled into one – including the initial conflict that leads to nascent romance between him and the Princess.
This is not to say that A New Hope is a straight remake of The Hidden Fortress – rather, the Star Wars film takes certain elements from Kurosawa and blends them into the space epic. The lack of certainty about whose side which characters are on and often sardonic humor further means that A New Hope owes quite a lot to its samurai forebear.