you sure about all that?
there were quite a number of Muslims where I worked, and a fair few that did Masters adn PhD courses there.
They were provided with a room to do the stupid prayer thing, and no-one seemed to care much at all.
i'm not sure on the residency thing, but I definitely know muslims that have been there 10+ years, have kids there, kids go to school and speak english, japanese and indonesian
Japanese generalyl don't feel strongly abotu religion and most loosely have two religions, shinto and bhuddism (depending on which particular festival/life event
)
I would suggest most of the christian japanese are in it for the free english lessons