Kamen Rider ZO is a 1993 Kamen Rider film produced to celebrate the franchise's 20th anniversary.
Geneticist Dr. Mochizuki splices grasshopper DNA into his lab assistant, Masaru Aso, who stumbles from the lab and goes comatose in the middle of the woods. Mochizuki's next experiment has even more dire results: He creates the Neo Organism, a diabolical mutant life form that holds him hostage when he won't complete its development. It creates a separate body for itself, Dorasnote , and tries to kidnap Hiroshi, Mochizuki's son, to force him to do as it demands, but he sends a telepathic call for help to Masaru, who transforms into Kamen Rider ZO to battle Doras.
Footage from the movie was used in Saban's Masked Rider, with ZO appearing only in faraway shots.
The movie was also adapted into a full-motion videogame by Wolf Team for the Sega CD under the title The Masked Rider: Kamen Rider ZO (not to be confused with Saban's Masked Rider), where it received a poor dub into English and also had scenes deleted. It was not well received.
There is also a novelization (which greatly expands on both Dr. Mochizuki and Neo Organism's motivations) and a manga (which adds a character and makes Dr. Mochizuki more of a traditional Mad Scientist).
ZO would appear in several later Kamen Rider movies, with the cameos being more minor as the years go on.
- Kamen Rider World (1994) - 3-D Movie crossover with Kamen Rider J
- Kamen Rider Decade: All Riders vs. Dai-Shocker (2009)
- OOO, Den-O, All Riders: Let's Go Kamen Riders (2011)
- Kamen Rider × Super Sentai: Super Hero Taisen (2012)
- Heisei Rider vs. Showa Rider: Kamen Rider Taisen feat. Super Sentai (2014)
Kamen Rider ZO provides examples of:
- Absent-Minded Professor: Hiroshi's grandfather. (The adaptations expand his role a little, and a Deleted Scene, where he shows up ready to protect Hiroshi with a lightning gun-rod and meets ZO, would've given him more of a Bunny-Ears Lawyer feel.)
- Adult Fear: Hiroshi, a young child, being hunted down by Doras and the Neo Organism.
- All There in the Manual: ZO is a prototype for Neo Organism, and wasn't supposed to be strong enough to win in a straight fight with Doras. However, Masaru absorbed enough energy from nature while asleep in the mountain for 4 years, and even gained certain abilities he didn't originally have, being able to return to his human form among them.
- Badass Biker Masaru on the Z Bringer.
- Body Horror: Neo Organism's true form.
- What it does to Dr. Mochizuki after capture.
- Claymation: ZO vs. Spider Woman Doras
- Cool Bike: The Z(et) Bringer. Transforms with Masaru, and is wreathed in green flames while doing so.
- Crossover: With Kamen Rider J in the short 3D movie Kamen Rider World.
- Daddy Had a Good Reason for Abandoning You: Dr. Mochizuki, though the reason for his becoming a Mad Scientist really isn't clear in the movie.
- Dark Reprise: The main song instrumental plays after the Neo Organism absorbs ZO into it's body.
- Giggling Villain: Neo Organism, though in this case it comes off as it being too young to pull off an Evil Laugh. The one it gives when ZO puts his fist into Doras during their last fight is extremely unsettling, with rising inflection.
- Homage: Of the original Kamen Rider. Most of the story elements, if you squint a little, are very similar to what was done in that show.
- Impaled with Extreme Prejudice: ZO ends most of his fights by impaling his enemy on something, either a weapon of some sort or his own fist with a Rider Punch.
- Implacable Man: Doras. no matter what he did, Hiroshi simply couldn't escape this thing. ZO takes its arm off? It just builds a new one. He runs it over with a motorcycle out a several story window, resulting in it falling on a jagging piece of metal and being impaled? It's put out of commission for the moment, but just gets back up and sends two monsters after the kid. It could give a Terminator a run for its money.
- Improvised Weapon: ZO has no explicit weapon of his own, but uses objects in his environment several times in battle. He even impales the Kumo Woman on a piece of her own leg he broke off to kill her.
- Laser-Guided Amnesia: Averted. While it appears that Masaru wakes up with no knowledge of who he is other then needing to protect Hiroshi, aside from being out of the know for a few years he actually remembers everything and is simply very single-minded about his new mission.
- Lighter and Softer: In direct comparison to it's predecessor, although admittedly, any entry barring manga works by Ishinomori' and season 2 of Kamen Rider Amazons would be this in comparison to Shin.
- Mad Scientist: Dr. Mochizuki. The novelization gives his Start of Darkness as being intense sadness when his wife died, with Neo Organism being an attempt at a lifeform that would never need to feel such pain.
- Mechanical Monster: The 'body' Neo Organism constructs out of junk is called Dorasnote . It is entirely unstoppable, and ZO has to settle for ramming it out a building from several stories up onto a sharp piece of metal, the first time they tangle. It doesn't seem to have any sapient intelligence at all until Neo Organism reveals itself at the factory - afterwards, Neo Organism appears to take direct control of Doras.
- Mook Maker: The Neo Organism is not only capable of creating Doras, but other monsters as well.
- Mythology Gag: Doras' henchmonsters are based on a spider and bat. And killed in that order, reflecting the first two Monsters of the Week in the original series.
- Naked on Arrival: Masaru Aso. (It's not clear in the movie if he was released or if he escaped from the operation that turned him into ZOnote , but he apparently ran for a while before falling asleep in a mountain.)
- No Name Given: Masaru Aso is never actually referred to by name in the movie. (A cut scene indicates that Hiroshi's grandfather would've called him by name in his ZO form.)
- Nostalgic Music Box: Hiroshi's musical watch.
- Novelization: Entitled Kamen Rider ZO: Boy in the Dark.
- The Oner: It's only about 1:40 long, but the first fight scene with Doras at the factory is all one take. The camera isn't mounted, and they fight around a central pillar - at one point, the camera operator is lifted up onto a walkway 3 meters up and lowered again as the fight continues below him.
- Punny Name: ZO's name was chosen because it resembled the number "20". The film was a commemoration of the franchise's 20th anniversary.
- Robo Cam: Doras has this ability and uses it to identify Hiroshi and ZO.
- From Masaru's portrayal to Doras's initial formation, the movie has a lot in common with another early 90s movie about a mysterious protector trying to save an initially distrustful targeted child.
- It's not too dissimilar to early episodes of the original series either; even Doras' shapeshifting isn't out of character for '70s Rider monsters.
- The Unintelligible: In the American version of the video game Doras's voice was distorted so badly he's practically impossible to understand. Worse, responding incorrectly to some of his dialogue will instantly kill you.
- Upgrade vs. Prototype Fight: ZO is the prototype Neo Organism, while the Neo Organism is the perfected version. Played with, as ZO was given an upgrade by the earth itself.
- Unwilling Roboticisation: Masaru Aso was turned into ZO by Dr. Mochizuki against his will.