Just a little thought I've been having. If WWI didn't happen, Europe may very well still be dominated by empires. This got me to thinking, Japan's a great power even by this point. How long would it be before Japan started marrying into the Euro powers?
Wouldn't it have been unacceptable to the Japanese that the Imperial family would have part-Caucasian blood? Wouldn't they have demanded racial purity? Japan historically has been intolerant of ethnic and racial differences. Marriages of people with ethnic differences would occur between Christians or people of the lower castes. Half-Asian and half-Caucasian people would be seen as the offspring of sexual slaves bought by the Portuguese or other Europeans. Generally, the Japanese consider themselves to be one race.