Mortgages for Japanese residents without citizenship or permanent residency
If you live in Japan and want to get a mortgage to buy a home, most banks require either citizenship or permanent residency. Shinsei Bank will make an exception if your spouse is a Japanese citizen or permanent residence. Another group of banks don't require any of the above.
Here are the Japanese lenders I've found that do not require citizenship, permanent residency, or a Japanese spouse. Where only some of the bank's loan products are available to non-permanent residents, I've called out the name of the applicable product(s).
Detailed requirements are listed on the 商品説明書 (Product Manual) tab
FAQ stating that you do not need permanent residency to apply for a loan. Sounds more non-committal than some of the others.
This page implies they may offer loans to people living in Japan without permanent residency. However, detailed requirements are not spelled out. The one-pager (PDF) for their My Home 100 loan actually lists Japanese citizenship or permanent residence as a requirement, so perhaps they make exceptions on a case-by-case basis.
Note that I have no experience actually trying to get a mortgage from any of these lenders. The information is provided as-is without endorsement or guarantee.