"Godzilla vs. Biollante" director and writer Kazuki Ōmori had initially hoped to start a standalone series centered on Mothra, and was in the process of rewriting a 1990 script for the unrealized film "Mothra vs. Bagan". The film was ultimately scrapped by Toho, under the assumption that, unlike Godzilla, Mothra would have been a difficult character to market overseas. The planning stages for a sequel to "Godzilla vs. Biollante" were initially hampered by Tanaka's deteriorating health, thus prompting the takeover of Shōgo Tomiyama as producer. The new producer felt that the financial failure of "Godzilla vs. Biollante" was due to the plot being too sophisticated for child audiences, and thus intended to return some of the fantasy elements of the pre-1984 "Godzilla" films to the series. Ōmori himself blamed the lackluster performance of "Godzilla vs. Biollante" on competition with "Back to the Future Part II", and thus concluded that audiences wanted plots involving time travel. His approach to the film also differed from "Godzilla vs. Biollante" in his greater emphasis on developing the personalities of the monsters rather than the human characters.