It's fairly boring, I'm afraid. Eiji Tsuburaya's special effects are superb and they've thought up some interesting script wrinkles, but it's still a snoozer.
Firstly, they keep you guessing about who their Invisible Man is. The film opens with a debate between three invisibility researchers. There's a young one who believes in blackness (Kyosuke Segi), another (Shunji Kurokawa) who's going for transparency and a third, older one (Dr Nakazato) who's happy to offer his daughter's hand in marriage to whoever develops the first invisibility serum. (No, really. Admittedly both young scientists have already proposed to her and she's been unable to choose, but even so. There's even room for dodgy jokes since the winner of that competition should technically be Nakazato himself, since he already has a working serum that he's been developing secretly for ten years. Unfortunately, its effects are irreversible and it makes its subjects irrational and violent.)
That's three possible candidates to become an Invisible Man. The film then introduces a fourth, when Dr Nakazato shows off his serum to a money-grubbing scumbag (Ichiro Kawabe). D'oh. A few scenes later, Nakazato's daughter goes shopping and is looking at a necklace worth millions.
The script's games with all that are moderately interesting. Fun is also had with the idea that it's possible to impersonate an Invisible Man, just by wearing a trenchcoat, bandages and sunglasses. I also loved the refreshing lack of scepticism from the police. No one in authority wastes time doubting everyone. Instead, they're taking the Invisible Man seriously and mobilising an army of cops with guns.
The script's interesting. The film isn't.
The cast tends to be dull. There are a few exceptions, but even them I wouldn't call anything special. Dr Nakazato's quite disturbing for various reasons, despite his twinkly-eyed good nature. (This might be deliberate, given the film's slightly contrived link of Invisible Men to the atomic bomb. "There is no good or evil in science, but it can be used for good or evil purposes." Then, at the end, Nakazato announces that he'll take all responsibility for thoughtlessly inventing something that brought disaster on society.)
Anyway, Dr Nakazato makes his daughter a raffle prize, shows his invisibility serum to crooks and will happily turn any and all animals invisible on a whim. Guinea pigs, cats, mice, etc. I wonder how many of his lab animals got out of their cages and starved to death without anyone realising. Nonetheless, the character's manner and story role are lovable cuddly innocence itself and I honestly don't know how the production team meant us to see him.
As for Ichiro Kawabe... well, he's villainous. You can't go far wrong with a villain. I also liked the policeman.
The rest of the cast are dishwater, though. The two young scientists are earnest and cardboard. They could have swapped roles and dialogue and you'd have never known the difference. The female characters are more important than you'd think, but equally one-dimensional. The film's romantic elements are as laughable as you'd expect given Dr Nakazato's bet. I didn't care. I got through the first hour okay, but after that I was bored. Furthermore, the plot's about stealing a necklace. Seriously? A necklace? I'm watching an Invisible Man film and that's the best it can do?
There are stupid decisions. The Invisible Man thinks there's an antidote. No one ever corrects this misunderstanding, not even someone who needs shooting for his failure to do so. Guess how well that turns out. Oh, and there's a cop who wants to do handwriting tests. He tears some pages out of Dr Nakazato's notebook (which contains all his irreplaceable notes), instead of just borrowing the book itself.
The special effects are impressive, though. This was one of Eiji Tsuburaya's earliest films as a special effects director, back in the American Occupation days when he was still blacklisted for having worked on wartime propaganda films. He got around that by starting an independent company and taking contract work, instead of being directly employed by the studios. Five years later, he did Godzilla.
The film's too polite and mannered, I think. It's not bad so much as insipid. The younger half of the cast don't have a personality to share between them. They needed some Universal overacting. The plot Macguffins are either too trivial to care about (the necklace) or end up making the Invisible Man a bit of an idiot (the non-existent antidote). Stronger acting could have made the latter compelling and tragic, but I wasn't watching that film. That said, though, there are other Japanese Invisible Man movies and I'm hoping they aren't all this weak. Invisible Man vs. Human Fly sounds promising.