Ad run in the March 20, 1975 edition of the "Honolulu Star-Bulletin."
In doing so, they are either unaware or dismissive of releases in Japanese-American movie theaters across the States - especially those in Hawaii - which were as legit as a grindhouse in Utah booking an AIP offering. There were Toho films booked into theaters in Los Angeles, San Francisco, New York, and Honolulu - months or years before a Stateside distributor.
Jun Fukuda's GODZILLA VS. GIGAN (1972) first opened in the US at the Toho Theater in Hololulu, Hawaii on March 19, 1975. Interestingly, the print booked was Toho's International English-dubbed version, as opposed to an English-subtitled print; likely to attract more children to the play dates due to matinee performances. So, this should count as the legit US premiere.
Some might argue that the Cinema Shares release was wider. While this was true, they never opened in more than a handful of cities at a time, over a long period - as there were only so many prints in circulation. While it played in some Southern states as early as the fall of 1977, following on the heels of "Godzilla vs. Megalon," other states didn't see the film until 1980.
Therefore, these Japanese theaters, and/or repertory houses, in larger urban centers (that includes Honolulu), were just as legit as any 42nd St. fleabag, suburban drive-in, or neighborhood theater in rural America. It's been long overdue to start looking at the bigger picture and to engage in some deep-dive microfiching through newspaper archives to find more. Or less.