Do they have any black people in Japan?
The only unpleasant interaction I had during a month in Japan was with a group of Africans on a Tokyo street who approached me out of the blue and tried a a mob-rob. It wasn't especially violent and they got nothing. Blacks are very rare. That was the only group of black people I saw in Japan, and they tried to rob me, lol.
Round eyes will likely be shocked at Japanese 'sexism.' It's just part if the culture. You walk in with your girl and they bow to you. They speak to you. The woman is very much in the background. Your gaijin girlfriend will not appreciate this.
The flip side is that men are afforded no latitude in terms of flakiness. You are expected to have your shit together, 100%, all the time.