For the 2022 "Godzilla Day", a self-proclaimed day by Toho that aligns with the anniversary of Godzilla (1954), the company commemorated the 50th anniversary of Godzilla vs. Gigan (1972). This included releasing two short films online: Gigan Attacks (2022) and Godzilla vs. Gigan Rex.
The latter, Godzilla vs. Gigan Rex, is a CGI-animated short directed and written by Takuya Uenishi. It can be seen as a pseudo sequel to his 2019 short film that he submitted to GEMSTONE's Godzilla contest titled G vs. G. Unlike the fan film, though, Godzilla vs. Gigan Rex was officially funded by Toho.
Produced by Shunsuke Yanagisawa and executive produced by Keiji Ota, the short was released under the GEMSTONE brand. It features Godzilla facing off against an army of Gigans, including Gigan Miles (who appeared in the fan film) and the new Gigan Rex. The short opens with narration by Megumi Odaka, who played Miki Saegusa in the Heisei Godzilla series. Her lines are:
"Once there was a fierce battle. And a quarter of a century has passed since you disappeared. People forgot, but thought it was fine because it has been peaceful. ...but, here they come."
The six minute short was released online on November 3rd, 2022. Toho later made it available on YouTube, where it remains accessible. Below is the short.
In an interview for the Godzilla vs. Megalon & Godzilla vs. Gigan Rex Original Soundtrack, director and writer Takuya Uenishi noted that the short takes inspiration from the Heisei "VS" series. As a result, he was conscious of taking music from that series when selecting stock themes.
On choosing Ludwig van Beethoven's Piano Sonata No. 14 "Moonlight" 3rd Movement, Takuya Uenishi noted this was something that came from the G vs. G submission he made for a Godzilla contest. Part of the stipulation for that contest was not to use the Godzilla theme, so Uenishi ended up selecting Beethoven's music for his submission. When Toho approached him on creating an official short, Uenishi wanted to include the same theme and ultimately decided to have it represent Gigan Rex. Discussed in an interview for the Godzilla vs. Megalon & Godzilla vs. Gigan Rex Original Soundtrack.
There was a heavy desire to include music from Godzilla vs. SpaceGodzilla (1994), as director and writer Takuya Uenishi felt it would have been at home to also represent the extraterrestrial Gigans. Ultimately, though, it did not make the cut and so instead Uenishi decided to include it in Godzilla vs. Megalon (2023) when it came time to make the next short. Mentioned in an interview found on the Godzilla vs. Megalon & Godzilla vs. Gigan Rex Original Soundtrack.