I've previously made some comment on how Japan has influenced costume design in Star Wars but I was dumbstruck when a friend let me know that the Star Wars saga was largely influenced by Akira Kurosawa and more specifically his movie's 'The Hidden Fortress' and 'Yojimbo'.
This comment from an online article I just read through:

Star Wars owed much to The Hidden Fortress in its inception. Lucas' original script was basically just a remake for Fortress, although even in the final edit many concepts from the film still remain.

The article explained specifically how this movie and Yojimbo influenced Star Wars and also what other influences Lucas had.