Created during the uncertain period of 1972, which saw several Godzilla projects aborted, Mogu was originally conceived as a partner for King Ghidorah and Gigan. The trio was to face off against Godzilla, Rodan and Varan in a screenplay that eventually was heavily altered until it became Godzilla vs. Gigan (1972).

Mogu was the brain child of script writer Shinichi Sekizawa, and was first thought up in the summer of 1971 as the next film began a long pre-production schedule. The flying creature, which was also able to fire a projectile from its maw, had replaced Megalon in a similar concept. However, unlike Megalon, after the project's eventual cancellation the creature was never reconsidered for a script again and has remained in obscurity.

Note: The picture seen above was created by artist John Rhodes using published artwork as a basis for use by Toho Kingdom. It was not created by Toho nor is it their official look for the unused character.