Kimono magazine, as the main element in a contemporary kimono ensemble. (By the way, I've mentioned Kimono before.)
It's funny how mainly just three flags get used iconically in design, perhaps each with associations attached. The flags of UK, the US and Japan all get used internationally. The UK for associations with the post-colonial, 60s, Punk, "Cool Brittannia"; the US for 60s, road-culture, cultural dominance, war and anti-war; Japan for the manga, cool samurai, pro-warrior and – perhaps more ironically – anti-war reasons. Other country flags may get used (China's or other red communist-country flags perhaps) but usually for limited or literal reasons, and most just don't make it into design generally.
Of course, there has been different dominance at different times across the globe from these three countries, but surely (?) it's as much – or more – the original design of the flags that allows their continued use in fashion and design.
The flag obi in the ensemble pictured is from modern antenna.