Sort of related, but here I'm asking about the virtual lack of anyone but people of Japanese descent among the recurring East Asian officers depicted in Star Trek.
Hikaru Sulu: Japanese-American (b. San Francisco)
Alyssa Ogawa: presumably Japanese or Japanese-American (based on first name?)
Keiko (Ishikawa) O'Brien Japanese (b. Japan)
Hoshi Sato Japanese (b. Kyoto)
Whereas, for other Southeast and East Asians, I cannot find any, really, except for:
Harry Kim (b. S. Carolina) has a typically Korean name and note this awesome clip of Garrett Wang, where he explains that apparently Kim was supposed to be Chinese, but even the actor himself didn't know he was Chinese until after the series ended.
And then in Discovery there's the beginnings of a slightly more diverse Asian contingent with merely:
What are the in- and out-of-universe reasons Star Trek seems to lean Japanese compared to other parts of the region?
I feel like I should also point out, that among those four starring/recurring Japanese roles, half of them are not even playing by actors of Japanese ancestry. So the character traits seem to have been set independently of casting with a preference to stick with "Japanese" despite casting decisions, even though the Japanese-ness of these characters (vs. say Chinese or Korean) wasn't really very central to them, at least until later writing (e.g. the ink brush flashback in "Violations" and influence in the Keiko/O'Brien wedding)