The film was released straight to television in the United States, in the winter of 1966 by American International Television as Dagora, the Space Monster.
When several TV satellites launched by the Electric Wave Laboratory go missing above Japan in Earth's orbit, it is found out that they have inadvertently collided with unidentified protoplasmic "space cells" of unknown origin. A similar creature suddenly thwarted the efforts of a local branch of the International Diamond Robbery Ring. The diamonds they sought vanished, and similar unexplained events continued to occur across the globe.
Meanwhile, Inspector Komai's (Yosuke Natsuki) investigation of these strange events led him to the crystallographer Dr. Munakata (Nobuo Nakamura). In the process of tracking down the self-proclaimed diamond broker Mark Jackson (Robert Dunham). He finds him in Dr. Munakata's home but knocks him out and escapes from Komai. He is then picked up by the gangsters for questioning. Komai wakes up and is greeted by Dr. Munakata and his lab assistant Masayo Kirino (Yoko Fujiyama). He tells them about the case he is working on and shows them pictures of the melted safe the gangsters were at that night. Komai then learns that the diamonds the Mark stole were synthetic and worth nothing.
Meanwhile, Inspector Komai escorts Masayo to her home. Along the way they meet Kirino (Hiroshi Koizumi), Masayo's brother who works at the Electric Wave Laboratory. They witness a strange invisible force suck up coal into the sky from a nearby the factory as well as flaming sparks from the clouds. They meet back with Dr Munakata who tells them that the flaming sparks might be from some form of carbon.
Later, the professional thieves took advantage of this ripe opportunity and attempted a heist on an armored car carrying the raw diamonds. But a nearby coal truck passing by is lifted off the ground by some unknown force and disappears into the atmosphere and is dropped back down to the ground. Unfortunately for them, they were fooled and escaped with nothing but candy.
The creature from outer space is deemed to be the culprit, an alien beast that draws its energy from carbon-based minerals. Dr. Munakata, confident in a remarkable scientific discovery, left for the coal mines near northern Kyushu, where it was proposed that the strange being would make its next appearance.
Mark Jackson also took leave for Kyushu, as the realization was finally made that the candy recovered at the heist was likely his doing. It was probable that he had, in truth, absconded with the true gems. Hamako (Akiko Wakabayashi), one of the gangsters responsible for the failed heist, prepared to double-cross her comrades and retrieve the diamonds for herself.
Over Dokaiwan Bay, as night fell, evacuation orders were put into effect as the jellyfish-like monster began to descend from the sky. The self-defense force fired, to no avail. The monster continued to absorb carbon-based materials wherever they could be located, and the abomination even destroyed the Wakato Bridge in the process. The military continued to unleash their artillery at the alien creature, and succeeded in momentarily silencing their foe. Unfortunately, the creature was only undergoing mitosis.
It is later found out that when Dogora is stung by the wasps, the venom causes a chemical reaction that crystallizes the space cell. Analysis of the crystallizing effects of the wasp venom on Dogora at the Medical Substance Laboratory proves successful, and mass production was soon ordered all around the world for the creation of a similar toxin.
Meanwhile, Dogora attacked once again, but this time, powerful artificial wasp venom quickly ate away at the creature. The robbers and the police clashed at the beach, and in the heat of a vicious gunfight, the gang was completely wiped out by a falling crystal boulder, once a section of Dogora's extraterrestrial flesh.
The wasp venom finally took full effect, and Dogora was no more. It was soon discovered that the diamonds Hamako had retrieved from the safe-deposit box were, in fact, synthetic. As this truth came to light, Dr. Munakata and his secretary left for the UN to discuss the peaceful potential of the Dogora incident with the world.
- Yosuke Natsuki – Inspector Komai
- Robert Dunham – Mark Jackson (as Dan Yuma)
- Nobuo Nakamura – Dr. Munakata
- Hiroshi Koizumi – Kirino
- Yoko Fujiyama – Masayo Kirino
- Akiko Wakabayashi – Gangster Natsui Hamako
- Susumu Fujita – General Iwasa
- Seizaburou Kawazu – Gangster Boss
- Yoshifumi Tajima – Gangster Zenichi Tada
- Hideyo Amamoto – Gangster Joe Maki Safecracker
- Haruya Katou – Short Gangster Sabu
- Jun Tazaki – Chief Inspector
- Jun Funado – Inspector Nitta
- Nadao Kirino – Gangster Gen
- Akira Wakamatsu – Gangster Pine
The film is unusual for Toho's giant monster series in that the creature is non-anthropomorphic and not portrayed by an actor in a costume. For scenes of it in its full form, the Dogora prop was placed in a small vat of water and puppeteered by people holding wires. This gave it the impression of it floating like an airborne jellyfish.
Originally, Dogora was titled (スペース・モンス Supēsu Monsu, lit. Space Mons) and was meant to be released in 1962.
Dogora's roar was reused for the Tsuburaya Production's TV show Ultraman, as the monster Bullton in ep 17, Passport to Infinity.
There were originally plans to feature Robert Dunham in a series of films based on the "Mark Jackson" character he played in this film. However, those plans never came to fruition.
As with its release of Attack of the Mushroom People, American International Television bought the rights to Toho's international dub in 1965 for television syndication. Since the film wouldn't play in US theaters, AIP-TV left Toho's English dub intact and added a new Dagora, the Space Monster title card. Allegedly, the name of the monster was changed to "Dagora" so that audiences wouldn't think the monster was a dog. Beyond the removal of the opening credits, the film was unedited. This version played for many years on late night TV and was released on home video by Video Yesteryear in 1983. The Media Blasters DVD uses the same dubbing featured in the AIP-TV version, but the edits are not retained.
- Teruyoshi Nakano- Director of Optical Effects
- Sadamasa Arikawa- Special Effects Cinematographer
- Takeo Kita- Special Effects Set Director
- Ken Sano- Assistant to the Director