Hey @Ewa Reza thanks for the post! Property prices in Japan have really been going up the past couple of years, especially in the Tokyo area, however capital appreciation is still a very foreign thing here.
The positives about the Japan market are solid cashflow, safe and stable tenants (evictions, etc. are just not a concern here as every renter needs guarantor individual or company which covers them when they don't pay rent, and rent is due before the start of each month), insanely cheap bank financing on very large investments, and a standard 5% fee for all property managers - who handle 100% of everything and mail you only to inform you if someone is moving in or out, there's a necessary or suggested repair, or with your detailed monthly report. Also the depreciation laws for tax savings have a couple of major loopholes which can save you a large amount on income tax.
The negatives are close to zero capital appreciation, a declining population due to the lowest birthrate globally (currently dropping 250,000-300,000 people a year), floating rate on most all bank loans (although it's a near certainty these won't be going up anytime soon as its been said if interest rates in Japan hit 2.5% the government would currently go bankrupt), and the highest debt to GDP ratio of any country in the world putting a dampening on future economic outlook.
For net yields you're looking at 3-6% in and around Tokyo, 6-8% in the other major cities, and closer to 8-10% outside of that, although there are always lots of exceptions. For investment property purchases, there are a couple of banks which will loan at between 2.775%-4.5% with zero down, and most major banks will loan at 1.5-2.0% with 10-20% down, but you need to either be a Japanese national or foreigner with permanent residency status in order to qualify. However the catch on both of these financing options is that you need to be a resident of Japan with income in Japan in order to qualify, so for those outside Japan the only options are to either purchase in cash, find outside financing, or link up with someone with said qualifications in Japan and either purchase through them or have them set up a company in Japan to purchase through (I know a couple here who was done that).
Hope you found this of some use and happy to help if you have any other questions!