It will be a struggle no matter if they're half-Japanese or not.

For who? A struggle for me, as in having a family that looks like the locals will not make things easier? Yes I was not planning on that but as they said Japan is a "one race nation" or whatever I don't think I would integrate if I took a girl from America with me (nor would it be easier). However your comment about the kids is unbecoming, I know Japan is sort of stereotyped as some sort of racist country (which I don't believe namely because of the low crime rates), why would a biracial child not fit in? They would speak the language, be at least half remniscient of the people in terms of looks, et cetera. Are you saying Japanese are racist?