@Miho Hatanakaundefined I am really late to reply, but though I agree with all comments offered before based on individual perspectives and opinions, I want to add my voice to the discussion just to broaden the dimension. I have a completely different experience because of my situation. I work on a US navy base and rather than turned down, we are heavily sought after tenants because owners realize that there are several advantages to leasing to military connected people: Rents are significantly higher, tenants don't disappear in the middle of the night although the required notice is quite short as people may receive relocation orders that require them to move quickly. There are numerous companies dedicated to market properties to tenants attached to the US base. Agents speak English and serve as intermediaries between owners and tenants. Helping to bridge the cultural gap as well.
What is absolutely true and affects landlord, tenant and neighbor dynamics is the cultural differences that invariable create friction. For example, Americans in general love to grill at home. Japanese people hang clothes outside and if the neighbor fires up the grill right bellow, clothing will be smelly and neighbors will be upset. Same with loud music at parties, parking on the street and a really big one is the garbage recycling. I've been told by Japanese friends that it is a big problem because Americans don't understand the recycling rules and sort the garbage incorrectly. These things can cause a landlord to turn a foreigner down because of not wanting to deal with neighbor complaints. The difficulty with communication may cause the foreigner to feel discriminated against when it can very well be that in true Japanese style, the landlord simply wants to avoid conflict.
In terms of purchasing, I agree that having to pay all cash for property is a deterrent. However a big positives to landlording in Japan is that your property is not likely to be destroyed by the tenant or vandalized during a vacancy.
I wish I could attend the BP meetups, but 2 hours away on a weeknight makes it rather tough, especially because if I stay to the end, the trains stop running before I can make it home. Anyone in Yokohama or Yokosuka wanting to get together?