On the matter of demographic pressures on Japanese public finance. While I certainly support the idea of free education through and including university for Japanese younger people and providing every opportunity for adults to conceive more children, and I think expanding immigration would, on the whole, prove a plus for Japan, these two things will not solve the government's fiscal imbalances.

1. Even if, overnight, Japan were to implement pro-natalist policies that boosted the fertility rate to more than 2.5 children per couple within one year, the impacts on the country's demographic structure, and its economic and fiscal position, would take decades to bear fruit.
a) Because children take 2 decades from birth to enter the labour force, and cost a lot of money to raise prior to that, the extra population would not contribute measurably to correcting the economic/fiscal imalances caused by ageing and low fertility for at least two decades, and more probably three or four decades. Indeed, in such a situation, the next two decades would prove a particularly expensive time for the government and people in bringing up all those extra children through to adulthood.
b) The total fertility rate fell below the 2.1 replacement rate for developed countries in 1973 and has remained below 2.1 since then. The net reproduction rate (the number of girls born to each cohort of women) dipped below 1 (replacement) in the 1950s (as I understand), and has been below 1 since the 1960s. That is now 50 years of low fertility, or 2 generations, more or less. The impacts on the demographic structure are so massive, that there is not any hope at all that Japan's population structure will move into replacement balance at any time in the next two or three decades.
After that, things may level off. But, right now there are just not enough (married) women of childbearing age to be able to have such an impact, even if there were a massive sudden change in conditions and sentiments towards marriage and childbirth, and even if life-expectancy were to be suddenly raised (older women do not have children, it has to be remembered).

2. The UN did some calculations back in the late 1990s on the impacts of immigration into countries with ageing and declining populations. You can find the document here:
http://www.un.org/esa/population/publications/ReplMigED
/migration.htm. Scroll down and click on the link for Japan. Reading the scenarios presented it becomes abundantly clear that the numbers required for immigration to have a decent impact on Japan's current population structure are so huge that it is an impossible task. We need to remember, also, that the document was published in 2001, and we are now in 2012, and the situation has got substantially worse in the intervening period.
It also needs to be remembered that immigrants are, on the whole, less economically productive than those who have grown up in a country. There are many reasons for this, with language being one and on average lower educational achievement being another. The above UN calculations do not, as far as I am aware, take these sorts of considerations into full account. It is probably the case that, if immigration were to be relied upon to solve Japan's long term fiscal deficits (rather than simply as a measure to achieve reproductive balance), then the numbers required would be even higher than the UN states.

There is not a snowball's hope in hell that any pro-natalist or pro-immigration policy is going to change Japan's economic outlook, at least wthin the next 20 years. Noda knows this and that is why he is not doing anything about Japan's demographic circumstances. He knows that, barring a miracle, the country's demographic outlook is set in stone and the government, instead, must simply accept and manage the situation on those terms from now on. Indeed, it may be good for Japan in the long run (if we take 50-100 years to mean the long run) that the population decreases to 70 or so million people.

Cheers.

Peter