Self-employed as a teacher or a company president? I would not loan money to a teacher or other contract staff either to be honest. They fall into the category of bad loan prospects due to no long term tie to Japan. Retired? The timeline to pay off a loan is up to 30+ years here. How do we know they will be alive? Debts of deceased parties in Japan are forgiven not passed on. Banks don’t want to take a bath. Investors buy homes all the time, and if Japanese have easy access to loans. If non-Japanese they may not have the credentials to even get a bank account, i.e. a resident alien card. I have to say, three very weak examples on which to base an argument.
Self-employed at any level makes it fairly difficult, at least for my experience. I know simultaneous interpreters, who are basically always self-employed (and get around 80k yen per day for more than 4 hours of work), who have had trouble. I knew of a Japanese teacher who started his own school and had 70+ students and had trouble. I have a friend who owns a chain of schools (with, I believe 10+ full-time teachers) who only used Citibank (not sure who he uses now) because he was tired of the nonsense from other banks.
If you are seishain banks generally love to lend you money, especially if your company is big/famous. If you're not seishain, it gets a lot trickier (this isn't just for foreigners but for Japanese as well).