While lack of any further news on any property damage and risk...

While lack of any further news on any property damage and risk of radioactive fallout in Tokyo seem to drive the SP down ATM, future prospects of AJA have actually improved by this dissaster.

Providing Tokyo will not be affected by follow up aftershocks and dangerous radioactivity, the real estate prices should improve. Destruction of so many houses, factories and offices in the earthquake affected regions will increase the demand for the unaffected properties all over Japan. After all, these homeless people have to go somewhere and do something. And they will.
Their demand should increase demand for reduced total number of properties available for rent or purchase.

I have heard an interview with institutional investment manager (unfortunately forgot his name or company) saying that they are buying into Japanese REITs, to cash on the expected rebound in real estate prices , once the situation in Japan returns to normal.

So I would expect the current drop in SP is only temporary.