Kamen Rider ZO (仮面ライダーZO, Kamen Raidā Zetto Ō), translated Masked Rider ZO, is a 1993 Japanese tokusatsubiopunksuperhero movie produced by the Toei Company as part of their Kamen Rider Series. Directed by Keita Amemiya, it was the first joint production of Toei and Bandai. A Sega CDinteractive movie was released for ZO in 1994, and was distributed in the United States as The Masked Rider: Kamen Rider ZO.
To commemorate the series’ 40th anniversary, ZO was shown on Toei’s pay-per-view channel in September 2011. The film’s protagonist, Kamen Rider ZO, appears in the later Kamen Rider Decade television series and is a playable character in the 2011 Nintendo DS video game All Kamen Rider: Rider Generation.
Masaru Aso is the laboratory assistant of geneticist Doctor Mochizuki. He is used in one of Mochizuki’s experiments related to the creation of the Neo-Lifeform, enabling him to transform into the grasshopper-like Kamen Rider ZO. He flees to the mountains and lapses into a two-year coma before he is awakened by a telepathic call to protect Hiroshi Mochizuki, the doctor’s son. After an attempt to discover the meaning of his transformation at Mochizuki Genetics, Masaru senses that Hiroshi is in danger and saves the boy from Doras as ZO. Masaru then reveals himself to Reiko and her karate class. ZO battles Koumori Man (created by Doras) to cover Hiroshi and Reiko’s escape, but they are sucked into a pocket dimension by Kumo Woman (which was also created by Doras). ZO saves them and kills Kumo Woman; Koumori Man snatches Hiroshi, with ZO in pursuit. After he saves Hiroshi, Masaru tells Seikichi (Hiroshi’s grandfather) that Mochizuki used him in his experiments. Refusing to believe it, Hiroshi runs off. Masaru finds him and fixes his watch, recognizing the melody which awakened him as he helps Hiroshi cope with the revelation. Koumori Man assumes Mochizuki’s form to lure Hiroshi away, and Doras knocks Masaru unconscious. Masaru awakens when a grasshopper shows him where Hiroshi has been taken. Making his way to a complex, ZO kills Koumori Man. He finds Hiroshi and Dr. Mochizuki, learning that the geneticist was the one who woke him up and that the Neo-Lifeform has been acting independently to become a perfect being. When ZO tries to fight Doras, he is absorbed by the Neo-Lifeform and Doras uses Hiroshi to force Mochizuki to complete its evolution. The music from Hiroshi’s watch keeps Doras at bay as ZO escapes from the monster, and Mochizuki sacrifices himself to destroy the pool (the Neo-Lifeform’s life source). The complex self-destructs as ZO and Hiroshi escape. Leaving the boy with Seikichi, Masaru leaves for parts unknown.
- Masaru Aso/Kamen Rider ZO (麻生 勝／仮面ライダーZO, Asō Masaru/Kamen Raidā Zetto Ō): The hero of the story, Masaru was Doctor Mochizuki’s assistant until Mochizuki experiments on him. Although he hates Mochizuki, Masaru eventually forgives him.
- Hiroshi Mochizuki (望月 宏, Mochizuki Hiroshi): A young boy who lives with his grandfather, Seikichi, and is targeted by the Neo-Lifeform. Hiroshi longs to be with his father, who went missing years ago. As a memento, Doctor Mochizuki gave Hiroshi a pocket watch which plays music. Hiroshi is afraid of ZO at first, but eventually calls him “Brother“.
- Doctor Mochizuki (望月 博士, Mochizuki-hakase): A mad scientist who turns Masaru into ZO and creates the Neo-Lifeform. Although he dreams of creating a “perfect lifeform”, it turns on him. Mochizuki uses grasshoppers to telepathically contact ZO.
- Neo-Lifeform (ネオ生命体, Neo Seimeitai): A pool of living fluid which relies on its container for survival. It assumes the appearance of a deformed, egotistical, unemotional boy resembling Hiroshi. It becomes the grotesque, Kamen Rider-like Doras (ドラス, Dorasu) to find Hiroshi and force Dr. Mochizuki to complete its evolution into a perfect life form and destroy the human race and its imperfections. Doras can regenerate after injury, absorbing materials to upgrade itself. When Doras absorbs ZO, it becomes Doras Strengthened Form (ドラス強化体, Dorasu Kyōkatai).
- Spider Woman (クモ女, Kumo Onna): A monster created by Doras, she is a four-legged spider who captures Hiroshi.
- Bat Man (コウモリ男, Kōmori Otoko): Another monster created by Doras, he is a black bat-like entity which can disguise itself as a human. As Mochizuki, it lures Hiroshi to its master’s hideout.