You’re fine to write outside your culture, you just have to do you research well. I mean really well. Go directly to Japanese sources to learn about traditional Japanese culture, not just random Japanese people, but scholarly sources too. Sometimes people don’t even know much about their own trad culture because Western culture has mixed things up so much (ex: many Japanese people believe Geisha are prostitutes, even though they aren’t). Basically, just make sure your research is very detailed and have beta readers from Japan too.
But this posts gives me the feeling that you don’t understand just how much culture affects a story. The way people talk, what they eat, how they eat, what they do in their free time, etc, is all affected by culture.
Example, I’m from the US and maybe I want to write a scene in which people from France eat. Americans spend an average of an hour a day eating, the French spend more than two hours. What are they doing while they eat??? Why do they spend so much time eating??? I would have to take this into consideration every time my characters want to eat.
So, in my opinion, you don’t just have to worry about traditional culture, which is where racial/ethnic issues come into play, but you also have o worry about pop culture and just everyday life. Other wise, your characters will feel like they are just Americans in a Japanese setting.
IDK if you’ve already taken this into account, but I think it is good advice or anybody writing about foreign cultures, real or not. You gotta remember that culture is “the way we live.” It affects everything.
