In 1963, Daiei Film offered members of the public fifty yen for every rat they brought to the studio. The cages soon filled a small warehouse.

The rats were flea-ridden, uncooperative, and increasingly diseased. The crew had to wear masks to work. The special effects director began muttering "rat, rat" in his sleep. The health department arrived and shut the production down. Roughly three thousand feet of footage had been shot. None of it was ever released.

NEZURA 1964 (2020) is a crowdfunded pseudo-biopic about the making of Giant Horde Beast Nezura, the cancelled kaiju film whose failure directly caused the creation of Gamera.

Directed by Hiroto Yokokawa, who had previously made a similar film about another piece of obscure tokusatsu history, it runs fifty-three minutes and was made in cooperation with Kadokawa, which now owns the Daiei library.

The cast includes veteran tokusatsu actors, and the film's theme song was performed by Mach Fumiake, one of the alien superwomen from Gamera: Super Monster, in the style of a Gamera march. The suit actor for the mammoth mutant rat creature in the film's new effects sequences was Akira Ohashi, who played Gamera himself in the Heisei trilogy.

The film takes the form of a dramatization shot in what one reviewer called "slightly above fan film" style, with a homemade quality it wears as a badge.

One of its notable choices is that Gamera is never named. The creation of the flying turtle is implied but not shown.

This is a film about failure made with visible affection for the people who failed.