Ask a simple question—i.e. “If you are a foreigner currently or formerly married to a Japanese citizen, did your spouse keep his/her Japanese family name after getting married to you?”)—and you will surely get an angry reply like this:

"I was married to a Japanese man, and yes - he kept his name. You seem to be assuming that the only people who marry foriengers are Japanese WOMEN. I happen to be a foreign woman who married a Japanese man. I kept my name because it's my name - why would I change it? Women don't "belong" to their husband; why should they change their name?"

Ugh. I wasn't assume anything. And why do you assume that as a man I was assuming something? Sheesh.

Statistically, Japanese men are far more likely to marry foreign women than Japanese women. This is something I have known for years. They tend, however, to marry other Asian women (Chinese, Filipino, Korean, Thai, etc.). Japanese women, on the other hand, marry in decreasing order Koreans, Americans, Chinese, British nationals, and so on.

What I am trying to look into—again, no assumptions; that’s why I’m asking—is what motivates people (particularly Japanese women) to either keep their Japanese maiden name or take their husband's upon marriage to a foreigner. Also, what motivates foreign men/women to adopt their Japanese spouse’s family name?

Ultimately, what I want to look at is what family name Western parents of half-Japanese children (i.e. children who are likely to look "half") are choosing for their kids and what motivates it. I also want to know what challenges, if any, they may have had if they had chosen the Western family name. 

One of my friends is half Japanese/half American, but looks for the most part like a Japanese man. Since his wife is Japanese, their children look, as you would suspect, Japanese. But, they all have his American family name written in katakana on their name tags at school. Whenever they change schools/grades and are introduced to new classmates, everyone is surprised by how good their Japanese is. Seeing the American name, the other kids brains assume the kids are 100% American rather than 75% Japanese. 

As for my own children, they look very . . . hard to say. They don't look Japanese at all, but they speak Hakata-ben and have my wife's family name. Wherever we go, people look at the boys and start speaking in broken English to them. 

Here are some stats on "international marriage": http://www.lifeaaa.jp/27.html

If you are a foreign resident in Japan who is married to a Japanese national, please have a look at this short survey at Survey Monkey.