Recently, Japan Government stated that they have intention to ease the restriction on the issuance of permission for permanent residence.
Currently, in principal 10 years’ residence in Japan is required to apply such permission with some exceptions including 5 years residence by persons who contribute Japan.
On the contrary to this current system, Japan might adapt 3 years residence requirement which might be imposed on persons who contribute Japan.
Japan is willing to accommodate highly skill professionals. http://www.immi-moj.go.jp/newimmiact_3/en/index.html
The easement of permission of permanent residence is one of the extension of this measurement.