After Mothra vs. Bagan was axed due to the underperformance of Godzilla vs. Biollante (1989) in theaters, director Kazuki Omori proposed a totally new screenplay in 1990 titled Mothra vs. Godzilla, where the titular giant moth would face off against Toho's most iconic monster. Though Bagan was never realized, Kazuki Omori very briefly played around with the idea of adding the demon beast to the film.
However, Omori started having second thoughts as he began to question if Mothra's appeal among audiences would be enough to keep the movie afloat, if the impact of her debut would be lessened due to the introduction of a new monster and Godzilla, and if this would cause a dip in video sales. Because of this, the short-lived screenplay went unused. To commemorate their 60th anniversary as a company, Toho instead began work on Godzilla vs. King Ghidorah (1991), as the three-headed monster placed highly in a "favorite monsters" theatrical poll among Japan's young male demographic.
A couple of years later, Omori would be given another chance at reviving the rivalry between Mothra and Godzilla. Using a heavily revised draft of Mothra vs. Bagan while throwing in what would eventually become Battra into the mix, the long-awaited rematch between two of Toho's most famous monsters would occur in Godzilla vs. Mothra (1992).