According to the June 11 issue of Nikkan Gendai, the vacancy rate for rental properties in the 23 wards of Tokyo is currently 33.7 percent, while in surrounding prefectures, it's even higher: 35.5 percent in Kanagawa and 34.1 percent in Chiba.

One real estate consultant told the newspaper that the combination of record-low interest rates and recent revisions to the inheritance tax law have spurred construction of new rental housing units by people of means who want to reduce taxes on the money that they will leave to their children. Nationwide, the number of such units built in April 2016 was 16 percent higher than the number built in April 2015.

The land ministry predicts that this year alone 430,000 units will be newly made available for rent. In contrast, between April 2015 and April 2016, the number of new for-sale housing units nationwide only increased by 1.2 percent. In Tokyo, new for-sale units actually fell by 7.9 percent during the same period, while new rental units increased by 20.1 percent.