A 1961 sci-fi flick (''Uchū Kaisokusen'', or "The High-speed Spaceship", in the original Japanese) famous for its appearance by a young Creator/SonnyChiba. What little plot there is concerns a gang of nameless Japanese children wandering around town and running into an invasion by the titular torpedo-headed Neptune men, some sort of "[[DeflectorShields electro-barrier]]", and Space Chief (''Iron-Sharp'' in the original), a superhero and "ineffectual chicken-headed bachelor" dedicated to fighting the Neptunian menace. Aside from that, it's pretty much ''PrinceOfSpace'' with added World War II stock footage (featuring a delightful cameo by Adolf Hitler) but without [[SoBadItsGood the charm of the Chicken Men of Krankor]].

For the ''Series/MysteryScienceTheater3000'' episode see ''[[Recap/MysteryScienceTheater3000S08E19InvasionOfTheNeptuneMen here]] ''.
!!This film provides examples of:

* AcePilot: We're apparently supposed to buy that Space Chief is one of these.
* AlienInvasion: A particularly slow, lumbering invasion carried out by about seven or so aliens equipped with endlessly looped weaponized stock footage. They try to spice things up by disguising the aliens as a brigade of transvestite soldiers, but it's still one of the least exciting struggles for mankind's future ever filmed.
* BlindIdiotTranslation: Whoever did the English dubbing was too lazy to try to get the dialog to sound like things actual English speakers would really say.
** Not to mention the "Roji-Panty Complex".
* TheCameo: Robby the Robot in toy form.
* CannedOrdersOverLoudspeaker: '''"DO NOT PANIC. DO NOT PANIC."'''[[note]]'''Mike:''' Yeah, ''right''.[[/note]]
* CoolCar: We're clearly supposed to think Space Chief's flying rocket car is super wicked sick, but even if it weren't made of cardboard and styrofoam you probably wouldn't want to have it.
* DudeLooksLikeALady: The Neptune Men when disguised as humans feature men wearing heavy pancake makeup, lipstick and mascara.
* FragileSpeedster: Space Chief's power. He's not invulnerable to the enemy lasers - he just has super-reflexes and dodges them.
* FreeRangeChildren: The kids' parents are not only never seen, they're never even ''mentioned''. They're so free-range, in fact, they don't even have ''names'' except the inevitable Ken.
** One of them is supposed to be the son of the facility's chief scientist. The rest? Who knows.
* GratuitousNazis: The infamous "Hitler Building," a stock footage building featuring a gigantic mural of UsefulNotes/AdolfHitler. It appears for a split second before getting blown up, and is never mentioned again.
* HongKongDub: The voices for the kids are incredibly stupid. Disregarding that, fairly standard for its time, but... gah, those stupid kids.
** Then there is all the other stupid voices in the dubbing, like Professor Froggy and Minister Sugar Bear.
** Even the normal voices are weird, since the above-mentioned BlindIdiotTranslation means that not only are the lines completely alien to normal English conversation, there's also the problem of matching up that dialog with the Japanese actors' lip movements. The result is something like Creator/WilliamShatner and Burgess Meredith doing a cold recitation of a particularly pause-heavy Creator/HaroldPinter play after a few strong drinks--except without a scintilla of the entertainment value such a recitation would provide.
* LandmarkOfLore: Tokyo Tower, the Japanese Diet building and, of course, The Hitler Building.
* TheLoad: The omnipresent Japanese children when they have to be saved by Prince of Space Chief. However, this trope is subverted as follows:
** The kids are the ones to discover and report the aliens, find the piece of the spaceship that is blown off, and deliver the device that the aliens use to communicate with the humans. They even notice the disguised soldier aliens before anyone else. They're actually more useful than Space Chief is.
*** Bear in mind that they were just the first ones on-site in both instances. Anyone with a pair of working eyes...or, failing that, ''one'' working eye, would have been able to see what they did. And be a lot less shrill when telling people about it. And probably cut down on all the running time by having a driver's license and car.
* {{Mondegreen}}: Many mishear the names Rojium and Tanium (radioactive elements named after two scientists in the film) as "Roji-Panty". The fact this is ''never actually explained'' in the English dub doesn't help, not that it would make any sense if it was explained, since all the character names have been changed around anyway.
* NonindicativeName: Space Chief is never seen to go into space. He's more like Lower Atmosphere Chief, really. Or Barely-Off-The-Stupid-Ground-Chief. Of course, those idiot kids gave him the name, so it's hardly his fault.
** In the original Japanese release he was known as "Ironsharp," apparently. This isn't really any better than Space Chief, since neither his ship or his superhero costume imply sharpness, with the possible exception of his table saw helmet.
* [[OverlyLongFightingAnimation Overly Long Fighting Scene]]: The infamous final showdown between Space Chief and the Neptunians lasts longer than most Music/{{Yes}} songs and is pretty much composed of the same few shots repeated ''ad nauseum''.
* ParentalAbandonment: No-one seems to care that the kids are just wandering aimlessly around town.
* SpaceClothes
* StockFootage: Lots.
** StockFootageFailure: Infamous for using footage from a 1960 Japanese UsefulNotes/ColdWar film ''World War III Breaks Out'', in what is supposed to be a kid's movie. Including the Hitler Building.
* StuffBlowingUp: You'd think a hostile spaceship reducing Tokyo to rubble would be exciting, right? Nope. Not a chance.
** In fact, this is probably the only movie in existence where the big, epic, action-packed climax is even more boring and tedious than the stuff preceding it.
* SureWhyNot: Space Chief apparently never bothered to come up with a superhero name, so when the kids just randomly call him that he rolls with it.
* SwissCheeseSecurity
* TokyoIsTheCenterOfTheUniverse: The aliens don't bother attacking anywhere else even though the only notable defense they face is a stationary shield.
* WeHaveReserves: Done in the most boring way possible.