Being a religious minority in Japan can be challenging in a variety of ways; at least 3 Japanese PMs have been Christian (Catholic x2 Baptist X1 off top of head). This is a deep topic of narrow interest; ask me over drinks sometime if you want the full geekiness about it.

You'll note that I did not dispute whether Japan was intolerant of other religions. How many PMs of Japan have been anything other than ethnic Japanese?

It is possible we may see a half-Taiwanese female PM in the future: https://en.wikipedia.org/wiki/Renh%C5%8D