When you hope to buy real estate for investment, you will care about which area you should buy.
You want to know which area, city is popular among potential renters.
In that case, you can look at this website.
Popular rank of potential renters in Japan
In the case of Tokyo, the number of potential renters who looks for apartment in Kichijoji ( 吉祥寺 ) is the highest in Tokyo.
face book invest real estate japan 2015.5/1