Of course from a political viewpoint you would have to question whether or not Australia actually wants to be Japan's ally.
IMHO Australia is an ally of all 3 country's. We had all our C-17 in Japan after the Tsunami/Nuclear meltdown .Experts and equipment was sent to assist Japan,in there time of need and was noticed and appreciated by the Japanese Government.
The RAN has trained with China's PLA-Navy ,that in its self would show a close and trusting relationship,add to that ,China is our biggest economic trading partner.
I would see Australia's role as a mediator between all 3 parties in resolving any disputes.
Japan may be interested in MK-48 Mod 7 CBASS torpedo's ?
Something that the RAN was involved with in developing with the USA.
I recall gf also stating we have some pretty good sensors for our Collins.
@ Blue Samari i am under the impression that Australia only want's drive train/engine tech off the Japanese subs.
Would be good to hear gf's take on this