[smcl]

Just out of curiosity - is it largely just "I only speak Japanese and don't know how I'd deal with a foreigner" thing or do those kinds of landlords tend to think negatively of the foreigners?

As an immigrant I know it can be a bit fiddly to resolve some things when there's a language barrier, but as long as both sides are patient and willing to try things can go relatively smoothly

[tjpnz]

In my own experience it's very much about the language barrier. I was able to smooth over many issues getting into my current place by mentioning my wife was Japanese.