The domestic Japanese publication industry certainly does carry enough weight to build a career as a professor on. The question is whether is actually should.
Many of the journals are essentially pay to play -- join an organization, present at the conference, write a paper for the proceedings that is not completely absurd (slight absurdity is ok), ship $100, and you will get published.
There are journals that are more rigorous, and getting into these at last once is often a key to better employment, but these are the exceptions rather than the rule. Furthermore, I would say that most of the work published in the competitive domestic Japan journals would not be publishable abroad both due to limited impact as well as (in some fields) questionable methodology.
As a simple example of the low quality that I found in some journals, many academics were unable to interpret standard t-tests correctly in their evaluation of their research. It brought a tear to my eye.
