Unfortunately, thousands will die ...
There is a huge health risk, unfortunately, and it may well kill tens of thousands over the next few months as a direct result of the reactor outage at Fukushima Daiichi.
See, Western Japan and Eastern Japan do not share an electricity grid; because of an historical accident, in the 1890s when they were first getting electric lighting, one utility chose to run at 60Hz and the other picked 50Hz. Consequently there's no grid interconnect between the two halves of the Japanese electricity supply system.
Eastern Japan has just had 15 nuclear reactors scrammed by an an earthquake. Some of them may be checked out and approved to start delivering base load again over the coming months, but they all need a thorough inspection at this point -- and we know for sure that at least three of them will never work again (not after they've had seawater pumped through their primary coolant circuit).
We are now heading into summer. And Tokyo doesn't have enough electricity to maintain power everywhere even in spring.
Summer in Tokyo is savage: temperatures routinely top 35 celsius with 100% humidity. In a heat wave, it can top 40 degrees for days on end. Back when I visited in 2008 the heat wave had broken and daytime temperatures were down under 37 degrees again -- the week before it had been over 42, and joggers had been dropping dead in the street.
Greater Tokyo also has 30-million-odd people, of whom a large proportion -- maybe 20% -- are 75 years or older.
Elderly folks do not handle heat waves well; they get dehydrated easily and if they don't have air conditioning they die in droves. Normally it's not a problem in Tokyo because 80% of households have air conditioning, but with rolling blackouts and insufficient power it's another matter. They can try and evacuate old folks into school gyms with aircon and portable generators, but the logistics of moving several million geriatrics are daunting, to say the least. Not to mention feeding them, keeping them hydrated, providing their medication, and handling sanitation.
If Tokyo experiences a heat wave this summer, the deaths (from heat stroke, among the other-75s) may well outnumber the direct fatalities from the earthquake and tsunami combined.