In all 3 countries local men married to a foreign (mostly Asian) wife outnumber local women married to a foreign man at least 2:1 or more, especially in rural areas.
In South Korea it goes even so far, that there are government programs concerning foreign women and their protection, as Koreans are not known to be soft-hearted people (Korean men and women can be very aggressive)
http://www.koreaherald.com/view.php?ud=20191122000436
-----South Korea will create a multi-language police hotline to better protect foreign wives from domestic violence, the gender ministry said Friday.
The government will also ban men with records of serious crimes from bringing in foreign brides and enhance education for marriage migrants and mix-race families to help them settle in this ethnically homogenous nation.
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The number of international marriages in Korea rose 8.5 percent to 23,773 in 2018 from a year earlier, according to government data released this month. Couples made up of a Korean man and a foreign woman accounted for 67 percent of the total.
About myself, I am an European man living in Japan since over 40 years. Many Western men I can say, expect something totally different in Japan and are grossly misinformed or ignorant of the way of life here.
If you don't have any special reason to marry into Japan and have no knowledge about Japan and language expect troubles. If you cannot find a reasonable job with a good income, then better stay away from Japan, and same is also true with South Korea and Taiwan.
Japanese women are not really into living with their Western husband overseas and usually prefer to live in Japan and keep good relationship with parents and relatives and also want 1 or 2 children. This costs all money of course. Don't expect that a salary as an 'English teacher without any qualification' is enough for a financially stable Japanese household.
Most foreign men I know from Europe who live in Japan since decades have a good income working for foreign companies, foreign government related offices, airlines, international hotel management, international schools and such jobs. Such jobs are only available in the larger cities and housing is at least 4 times more expensive than anywhere else in Japan.