When Mystery Science Theater 3000 (MST3K) was rebooted in 2017 following a successful crowdfunding campaign, Reptilicus (Poul Bang/ Sidney W. Pink, 1961), a cult Danish-American co-production, was the subject of the first episode's riffing. The choice was perhaps not surprising given the original MST3K's passion for ‘bad’ monster movies. The first run of the show had featured numerous Japanese monster movies. This opening takes its title from a song by Jonah in the reboot episode: ‘every country has a monster it's afraid of’. Usually, as Jonah’s rap shows, these creatures have roots in folklore or mythology, and while this is true of some big monsters, this isn't necessarily the case for most kaijū. As many scholars have shown, kaijū were born of the atomic nightmares of the twentieth century. The Godzilla (1954–present) series is really the kaijū eiga's urtext. The genre has grown over a century, and national and international resonances have shifted throughout that time. Transnationalism has therefore become the most useful concept through which to explore how national and global themes have been shaped by cross-border exchanges, appropriations or political and environmental concerns. Even as globalisation undermines the stability of borders, national specificity remains an important concern, and this shifting, mutating form has roots and branches in many countries, and as Deborah Shaw (2013b) has argued, the national film remains a vital concern in transnational cinema studies. Even though every country has a monster, kaijū have very specific associations with Japan.

This is really a book about global connectivity. It isn't intended as an authoritative overview of every global kaijū movie, but as a look at genre through an interpretative lens. The kaijū eiga is thus a case study for a point of view that might be applied to other transnational genres. What is perhaps most immediately revealing about the kaijū eiga is that, unlike many international film forms, its name borrows a Romanised Japanese rather than Anglophone term. Fans and critics use the Japanese word to refer to the genre, and kaijū has become a loanword in English-language films such as Pacific Rim (Guillermo del Toro, 2013) and Monster Island (Mark Atkins, 2019).