Brit here, spent a year teaching in Japan and have lived in the USA for a few years.
I think it is broadly true that women seem more attracted to foreign men; the same doesn’t seem to be true to the same extent in the other case: men aren’t into women purely because they are foreign. If you have an RP British accent in the USA and are reasonably attractive, prepare for hot women to start conversations with you on the slimmest pretext as soon as they hear you talk.
(Ironically enough, I’m a bit of an exception: I find foreign girls very attractive, and what attracted me to my American wife was that she wasn’t overawed with my nationality, and didn’t immediately drone on about ever foreign trip she’d ever taken and every foreigner she’d ever met.)
In Japan, there was a very weird dynamic. Amongst my (white) western friends, the guys definitely did have a lot of luck with the local population. The girls had a much harder time of it.
There seemed to be a few layers to this. First, even in the noughties, the girls seemed to be used to getting hit on rather than doing the hitting. So when the white guys weren’t hitting on them anymore, and the local guys weren’t either (too afraid/language barrier), the western girls were a bit lost. They got it at both ends: they couldn’t get the local guys for various reasons, and they couldn’t get the white guys either, because they were balls deep in the locals.
This led to a certain amount of bitterness on the part of the white girls, who used to mutter that the guys just wanted a subservient doll. Part of this was obviously just defensiveness, but there was a fair amount of truth to it too. Amongst the American and Canadian guys in particular, there were a lot who (openly) wanted a Japanese girlfriend because they were ‘more feminine’, where that was a code for more subservient, etc.
The language barrier was an issue, too: Japanese girls are generally better at English than Japanese boys. So monoglot English white girls had a very limited dating pool.
But what some people have said about the image of western men was true, too. A female Japanese friend of mine told me that they thought North Atlantic men were more likely to buy them flowers, and whatnot.
pdts