[BoringTimesGang]

It's not a 'Japan thing'. I pay a higher rate on my mortgage because my spouse was not a citizen of where we live when we took it out. There are fewer providers willing to offer mortgages in this situation but, presumably, there's still enough of a price incentive that the premium isn't pulled out of thin air.

It's also common for landlords to ask for higher deposits or months paid up-front.

[esperent]

It's also possible that the banks have less legal requirements to non-citizens so they make up a bullshit reason for charging you higher. Which is absolutely something a bank would do.