Basically, making a story that takes place in Japan and I want two twin girls to be in the story. These twin girls speak Japanese but are not from Japan and I would make them, say, English if it were in the USA or Portuguese if it were in Brazil, but Japanese is only really spoken in one country. I suppose there are, however, other countries with a large Japanese-speaking population. Maybe they could be Japanese-Brazilians? Grew up with the Japanese language and all, just born and raised in Brazil and came to Japan later in life?