Toho Company Ltd., the makers of Godzilla, was going to sue Japan Radio Pictures, as they thought Agon looked too much like their famous monster. But when they found that director/writer/SPFX director Fuminori Ôhashi (who helped out in making the first Godzilla suit) was working on the show, Toho simply said, "Oh, it's you! Well, it's okay then!"
The Agon monster suit was remade for the superhero TV series Maguma taishi (1966) (known in the U.S. as "The Space Giants"), first as a Giant Dinosaur in Episode #1, and as the fire monster Aron in Episodes #13-16. Contrary to popular belief, the Agon suit was not modified into the Aron suit, and were actually two different suits. (Japanese magazine books have featured pictures of the two suits for a side-by-side comparison, and the suits have a somewhat different build; only Aron looks noticeably more refined.) Both suits were made by Fuminori Ôhashi, who was an effects supervisor on both series.
Although four episodes of Agon: Atomic Dragon were complete by 1964, Toho used the no-compete clause in creator Shinichi Sekizawa's contract to prevent them from being broadcast for four years, citing Agon's resemblance to Godzilla.
The series was originally set for 26 episodes, consisting of 13 two-parter stories. (Only the first four episodes/two stories got made.) At one point, Agon was going to be bombarded with a nuclear weapon, which would cause him to grow dragon-like wings on his back. Some episodes have him defeated by being lured into a volcano in one story, to the North Pole in another, and he would eventually be killed by a special super-ray weapon in the series finale.
Originally filmed in 1964.