[rsync]

Also, he mentions (low) cost of borrowing as a key point to his thesis, but my understanding is that the cost of borrowing for Japan is heavily influenced by domestic savings.

IIRC, a lot of the money "borrowed" are the contents of the postal savings accounts (or whatever they are) of elderly Japanese who are extremely conservative investors. I have further seen it commented that there will be complications when that sect of the population switches to net withdrawls as they near end of life or pass on inheritance, etc.