Gamera has the general configuration of a turtle, albeit a tremendously large one that is capable of walking on two legs and flying, though he occasionally walks quadrupedally in his first three films.
Gamera demonstrates the ability to manipulate objects with his forefeet. He possesses a pronounced sagittal crest on top of his head and his mouth is filled with teeth, a precedent unheard of in turtles, save perhaps for the prehistoric turtles, and a pair of large tusks protruding upward from the lower jaws.In the Shōwa era series Gamera was a titanic, fire-breathing, prehistoric species of tortoise who fed on petroleum-based material presumably giving him the ability to breathe fire and fly by "jets" ignited when the monster retracts its legs - it can propel itself by spinning through the air with all 4 legs in and (shown in later films) can fly straight with just the rear legs drawn inside its shell.
The original movie bgins showing bombers of the U.S.S.R. being intercepted by American fighters over U.S. air space in the arctic (the intrusion may not be intentional). The Soviet pilots refuse to be forced down because of the presence of atomic bombs onboard their aircraft so they attempt to leave the area. However, the fighters launch an attack and one of the bombers crashes into the ice. A nuclear blast ensues as does the release from suspended animation in the ice of a 200 foot long turtle. The incident unfolds over the heads of a Japanese research team who have stumbled upon an Eskimo tribe in possession of an artifact, an ancient stone etching, that suggests the giant turtle (maybe more than one) had been observed and duly noted at some earlier time in mankind's history. the moniker "Gamera" has already been given to the beast as the tribal chief relates to the researchers. The body of the film gives the impression that Gamera is a creature whose unusual adaptions must have somehow evolved in the latter part of Earth's early ammoniac, carbon-dioxidal atmosphere.In the Heisei era series, however, the origin of Gamera was tweaked to make the theme much more directly heroic: a bio-engineered Guardian of the Universe created by Atlantis with the purpose of defeating Gyaos, another ancient creation capable of killing all human life. The giant turtle is found floating adrift in the Pacific, encased in rock and mistaken for an atoll.
Within the rock, investigators discover a large monolith explaining Gamera's purpose, as well as dozens of magatama, which allow a psychic link between Gamera and humans. In the third film of the series, an undersea graveyard is found with many other Gamera fossils, suggesting Gamera was not the only member of his kind created. One character in the film refers to these fossils as "beta versions" of Gamera, possible failures in Atlantis' attempts to create the final version. Another scene provides Gamera with a link to Asian folklore, with a character relating a story in which a giant tortoise is considered the Guardian of the North, with separate, rival creatures defending the East, West and South. Gamera's continuity was rebooted again in the only film of the Millennium era.
The film begins with the original Gamera sacrificing himself to destroy several Gyaos in 1973. 33 years later, a young boy finds a strange, glowing red rock near his home, with a small egg lying on top of it. A fairly normal looking baby tortoise soon hatches from the egg, but begins to grow at an alarming rate. The turtle, now named "Toto" by his preadolescent owner, quickly develops Gamera's classic abilities to breathe fire and fly, and attempts to ward off another attacking monster, Zedus, but is too weak to succeed. Only after eating the glowing rock found with his egg does the new Gamera achieve his full power, defeating Zedus and flying off into the sky.