Thanks to John Campbell for raising this interesting discussion. Aurelia's response was particularly interesting. I know the dialogue is primarily about politician-bureaucrat relations, but just want to mention that a "Westminster"-style cabinet government also depends upon 1)unified and strong party top-down cabinet leadership and 2)a primarily unicameral system.
Japan has had neither of these. It is important therefore to also keep our eyes on Abe's ability to impose 1)on the LDP (remember the DPJ tried it and had to backtrack from top-down cabinet government) and whether reforms and LDP's victory in 2013 HOC election make it any easier to get around the many obstacles involved in 2).