The 50k JPY figure comes from the budget for social welfare in Japan. Here is an article where it is broken down for 2009:
http://diamond.jp/articles/-/16672But, let me try it with figures from 2011.[1]
107,495 billion JPY for total social welfare
32,463 billion JPY for national health insurance
The author deducted the amount spent for national health insurance from total social welfare.
That leaves:
75, 032 billion JPY
It should only be for the adult population, but I can't find numbers for just adults, so I divided by 120million.
625,266 JPY annually
or
52105.5 JPY a month.
IIRC social insurance is not included in the general budget.
As far as the 170k JPY calculation, that was just my imagining what would be a reasonable basic income. I have never crunched the numbers on it.
But, it comes out to 2.04 million yen a year. Since the GDP per capita in Japan is 3.76 million JPY, this would be quite the redistribution of wealth.
[1] http://www.ipss.go.jp/ss-cost/j/fsss-h23/h23.pdf