In the film, authorities deal with the attacks of Gamera, a giant prehistoric turtle unleashed in the Arctic by an atomic bomb.
Due to a low budget and tight schedule, Yuasa was forced to use outdated equipment, faulty props, and faced belittlement from colleagues.
A localized version with new footage was theatrically released in the United States on December 15, 1966 by Harris Associates, Inc. and World Enterprises Corporation as Gammera the Invincible.
Japanese scientists on an expedition nearby, Dr. Hidaka, his assistant Kyoko and reporter Aoyagi, are given a stone tablet by an Eskimo chief, who explains that the creature is called Gamera.
In Sagami Bay, Toshio (a boy recently forced to release his pet turtle) and his family encounter Gamera, who attacks their lighthouse.
Upon returning to Japan, Dr. Hidaka, Kyoko, and Aoyagi accompany the military when Gamera approaches a geothermal power plant.
The bombs postpone Gamera's assault as the military rig the area with explosives and succeed in turning the monster on its back.
Meanwhile, disasters and accidents start to occur: Koto Ward is struck by flash floods and ships collide in Tokyo Bay.
As Nobuyo searches for her brother, Toshio makes attempts to breach restricted areas to see Gamera until he is caught at Oshima.
The next day, the Z Plan is put into action: Gamera is lured into the nose cone of a giant rocket and launched to Mars.
[17] Takahashi then wrote a four-page treatment titled "Fire-eating Turtle Attacks Tokyo" (Japanese: 火喰いガメ 東京を襲う, Hepburn: Hikui Game Tōkyō wo Osou).
[1] Yuasa inherited the Gamera assignment due to Nezura and was constantly belittled by studio execs and colleagues who believed the film would fail and would never compete with Godzilla.
Tsukiji's concept artwork was handed over to art director Akira Inoue and independent consultant Masao Yagi for further sketch designs and clay models.
The Gamera suit was made to walk on all fours to make filming easier and distinguish it from other upright monster characters.
"[22] The Japanese footage was dubbed into English by Titra Studios, which featured the voices of Peter Fernandez, Corinne Orr, Jack Curtis, and Bernard Grant.
Tadashi Yamanouchi's score was left intact while additional music recycled from film libraries was added to supplement the new footage.
This English dubbed version, simply titled Gamera, as well as the others released by Sandy Frank, were featured on Mystery Science Theater 3000.
[1] The project was considered "cheap" and "destined to flop" among filmmakers partially due to the financial situation of Daiei Film.
[9][4] A heavily altered version of the film was theatrically released in the United States on December 15, 1966 as Gammera the Invincible by Harris Associates, Inc. and World Enterprises Corporation.
After acquiring World Enterprises and their catalogue, National Telefilm Associates released a 16mm pan and scan version to television.
Gammera the Invincible usually aired alongside the English versions of the Gamera films released by American International Television.
It was this 16mm pan and scan version of the American cut that became the source for many public domain VHS and DVD releases in the United States and Canada.
[28] Keith Phipps from AV Club stated "Gamera finds the perfect intersection between silly and cool, looking both dangerous and ridiculous as he tromps around.
"[29] Arnold T. Blumberg from IGN awarded the film 6 out of 10, stating, "Gamera retains a kitschy charm but it was an inauspicious debut for a beloved icon.
"[30] James McCormick from Criterion Cast called the film "a wonderful slice of schlock that you can watch again and again and appreciate the workmanship and love put into every scene.
"[32] Years later, effects director Yonesaburo Tsukiji dismissed Sagisu's allegations and claimed that Masaichi Nagata's son, Hidemasa, conceived the idea for Gamera.
Factory included the Mystery Science Theater 3000 episode featuring the Sandy Frank version of the film on the MST3K vs. Gamera DVD collection.