I refuse to call this film "Tidal Wave", "Submersion of Japan" or any of the other names that you'll seen on the internet. "Nihon Chinbotsu" means "Japan Sinks". I'm also reviewing the 143-minute Japanese original from 1973, not the 82-minute U.S. release from 1975 that was edited by Roger Corman.
As far as I can tell, this film is better regarded than the 2006 remake... but personally I preferred the latter.
WHAT'S BETTER ABOUT THE 1973 FILM
It's more iconic. It says it's going to destroy Japan and, yup, it does. It doesn't mess around with significant romantic subplots, children whose mothers are in comas, etc. (It has an insignificant romantic subplot, but never mind that.) The film's focus is clearly and squarely throughout on putting Japan under the waves, although admittedly a good hour passes before there's even any pre-carnage. The crowd scenes are huge, especially at the beginning when we see lots and lots of Japanese people at festivals, etc. Because they're almost all going to die. The film's death toll is many millions. At times, our heroes would be delighted even to save five per cent of the country's population (then 109 million).
The visual spectacle is pretty good. They didn't have CGI in 1973, obviously, but the modelwork is high quality and they use an insane number of extras. We see people burn to death. There's even black humour. "Just don't start a fire!" says a man to his family, shortly before they drown.
The film's also pretty good on the international angle, covering this far more thoroughly and plausibly than the rather odd nationalism of the 2006 film. We meet quite a few English-speakers as the Japanese government negotiates with ambassadors, prime ministers and the UN.
WHAT'S WORSE ABOUT THE 1973 FILM
It's a disaster movie.
Yes, I realise that it's dumb of me to watch a disaster movie and complain that it's a disaster movie. Next week, I'll be outraged that rain is wet. The 2006 remake, though, felt like a story about people. It never lost touch with what its characters thought and felt, even (especially!) when they were being weird.
This, on the other hand, reminds me of dull 1950s monster flicks. It really is a movie about a disaster. Characters? Sod 'em. They exist, they talk and a few of them even have personalities, but it's rare for the characters to be the focus of a scene. The film's well-paced, convincing, has shocking destruction, etc. but ultimately it's the story of a natural disaster.
There's a romantic subplot that's just as flawed as the one in the 2006 remake, but in different ways. It's more credible. You'll never roll your eyes. It is, though, tokenistic and arguably a bit sexist (albeit in ways that reflect the era). The film's protagonist-oid (for lack of a more suitable word) is Onodera, played by Hiroshi Fujioka with manly 1970s hair and sideburns. Someone tells him that he should get married, so he goes off and meets a hot rich girl who sleeps with him almost immediately and is thereafter in love with him even though he soon returns to his disaster movie scenes and pretty much forgets her. She has no job, role or usefulness. Her plot function is to be "the pretty girl who fancies the hero".
I'll never rewatch this film. Frankly, it was a bit of a slog getting through it once. (If your eyes never close, give yourself a gold star.) I don't mind the fact that it's long, slow and talky. I like its 1970s-ness, which in my opinion is the best thing about the film and gives it an immediacy that I particularly associate with that decade's cinema. It is, though, a very literal, straight-as-an-arrow take on the admittedly attention-grabbing concept. It's never weird or odd. It doesn't really spare much attention for its characters. It thinks we're here to see Japan sinking and that's the overwhelming focus of its 143 minutes.
This film has the kind of script that you'd find it almost impossible to make yourself write, because you'd be aware deep down that its scenes aren't really saying anything about people.