Harakiri is probably my favorite Japanese movie
Yes.
Double yes.
With the two GOATs covered, some deeper cuts from Criterion I adore:
The Human Condition Trilogy (1959)
Is it possible for man to be good? Is it possible for war to be just? An idealistic Japanese man is sent to Manchuria and determines he will run a slave labor camp in a morally right way. Things go poorly.
Twenty-Four Eyes (1954)
A new teacher watches as her students, and Japan, deal with the some of the most traumatic decades in modern history. Starts off as a cute family movie then spirals rapidly as things go from bad to worse.
Kwaidan (1964)
Do you like ghost stories? Do you like art? Well I got art all over your ghost stories, I hope you like them.
Dawson City Frozen Time (2016)
A bunch of old nitrate films found in a frozen pool tell the story of the twenty first century, America, and the creation and evolution of film itself.
A Legend or Was It? (1963)
What if Harakiri was a scathing rebuke of wartime civilian submissiveness to authority? And had female leads?
Moonlight Serenade (1997)
I saw it described as 'Titanic but Japanese' and it kinda is, an epic and sprawling historical drama about a family trying to go back to normal after WW2 (and spend a lot of time on a boat).
Under the Blossoming Cherry Trees (1975)
Do not look up anything just watch it.
And just real quick recommendations: Picnic at Hanging Rock, The Thick Walled Room, Morning for the Osone Family, Fantastic Planet, Farewell to Dream, I Live In Fear, Narayama, Ugetsu, Dear Zachary, M, and Carnival of Souls.