I don't think the issue is about "becoming" any of those nationalities you mentioned. You might not be considered Indian or Nigerian or Kuwaitian in those countries, but you sure as hell won't be ostracized or receive disapproving looks. That is speaking generally since every country has racist/xenophobic people.
Blackface is quite common in Japan. Example: https://www.bbc.com/news/world-asia-42561815
They have more work to do on their attitude towards foreigners than opening up more immigration channels.