Population growth is zero:
Japan's population is projected to shrink by approximately 32 million persons, or 25%, over the next forty years:
Assuming an average household size of two persons, this would mean that about 12.5 million housing units would become excess during this time frame. That would be a significant drag on residential real estate values.
At the same time this would imply reduction of commercial real estate values, as fewer consumers would mean less need for retail space; while reduction in employment would mean less need for office/work space.
It seems that domestic sectors will be a drag on economic growth for Japan for the foreseeable future. At the same time, as export markets are stagnant or in recession it is difficult to forecast much growth for Japan's export sector.