I will also chime in and put forward a full recommendation for all four of these films. I would also vouch for The Hidden Fortress, which is an amazing watch when you know going in that it's the plot basis for Star Wars.I mean, yes, other than Seven Samurai, Rashomon, and Ran.
But for sure, make time for Harakiri - the movie, not the practice.
If you want Samurai-adjacent films, I can recommend two from the '60s that have just a ton of flair. Tokyo Drifter (1966) is technically a Yakuza film, but the story line is really a throwback to the Ronin (i.e. "freelance Samurai") genre. The second is Le Samourai (1967), a French-Italian co-production featuring Alain Delon as hitman in an intriguing interpretation of the "samurai" genre. Both of these movies just have style for days.