I'm embarrased to admit I avoided this film for years, despite its appearance in several curated movie collections, because it looked rather bad. Fortunately I finally caved after watching other Matsumoto films that were creative, hilarious, sad and unique, with deeper layers beyond their insanity as to never succumb to being weird for weirdness sake alone.
Dai-Nihonjin shares all these strengths with the dryness levels on the humour-knob turned up to severe skin-chafing levels. This will put off many viewers not familiar with this style of japanese comedy best exemplified by the cult director SABU's filmography.
As a deconstruction of tropes this is a rather genius work of art. The faux-documentary style enhances the absurdity of the situations and at the same time gives real weight to the plight of the hero, the eponymous Dainihonjin.
Turns out having to be a hero sucks, it destroys your life, nobody likes you and maybe you're only making things worse for everyone.
A lot of what makes this movie so charming is the intentionally bad CGI for the creatures that are somehow both hilarious and oddly terrifying. It reminded me of the bizarre existentialist Dreamcast game Seaman which is always appreciated. There are so many clever elements here that are always glossed over in other movies or comics like this. Just how do you solve the whole underwear problem when you grow from human to giant size and back?
Beneath the comedy there is some genuinely smart commentary on the media, society and strangely enough international relations of Japan to its neighbors. While this is presented in a rather understated and subtle manner, being played straight thoughout, it all eventually erupts like a comedy volcano in the final ten minutes and just totally bludgeons you over the head. I can't remember the last time I've laughed this hard. I was in actual pain.
This is a hard film to recommend to more mainstream audiences but it's so genuine, creative and hilarious that it deserves more viewers.