I think the issue with black SMV maximization in Japan is that you are best off going to the most densely-packed, cosmopolitan areas of Tokyo like Shibuya. These are the only places you'll find appreciable numbers of girls who are into black culture and black looks. But guess who's around you? A million black tourists! As a black male in Tokyo you're going to deal with serious saturation issues.
The pipe dream fantasy of getting a cute village girl in a town in the mountains is probably not going to work out well for black folks. East Asian + white only.