I would agree with Kirei_na_me. My BF is Japanese, he says that it's not so usual for Japanese men to date non-Japanese women (more usual the Japanese woman to date non-Japanese man) but it is certainly altering, but slowly. In fact, he is kind of at the older end of young, so the younger generation probably more open-minded. BF says that Japanese not generally so open for such relationships, but he thinks this is not really a good thing (especially given the falling birth rate), on the other hand, his attitude maybe not what you'd call 'stereotypical Japanese' so I don't know...
Lol I haven't added anything whatsoever to this discussion except drivel!
Although I did wonder whether he's an agent employed by Japanese government to increase their population