Japan sees its bid for Australia's $50 billion submarine program as just one step in deepening defence ties that would also see the two nations' navies work closely together on joint operations such as enforcing freedom on the seas.
The visiting delegation from Japan, which is bidding for the hotly contested program to replace the Collins Class submarine, says choosing Japan over rivals Germany and France would help cement the natural bond between the two major democracies of the western Pacific. 
In comments that are likely to raise hackles in Beijing, senior Japanese defence official Masaki Ishikawa told Fairfax Media that Japan would like to go much further than just building Australia's next subs.
"We would like to deepen our strategic co-operation with Australia. So we don't want to stop at the submarine building co-operation itself. We want to go further to operational co-operation in the submarine area: joint training, joint operations, something like that.   Maybe the US could join us [in a] trilateral operational co-operation," he told Fairfax Media on the sidelines of the Royal Australian Navy's Sea Power conference in Sydney.
"Two democracies and two such allied countries of the US - we can co-operate in keeping the Pacific safe."
The strategic argument to buying Japanese submarines remains a central plank of the country's pitch to Australia. The two countries' navies would be closely bound together by using the same submarine technology.
It was a dimension enthusiastically embraced by former prime minister Tony Abbott, who believed that Canberra and Tokyo should deepen ties amid the rise of China and the strategic uncertainty that this is causing, though this outlook is expected broadly to continue under Malcolm Turnbull.
But the desire for closer ties on both sides - a fact clearly reinforced by the Japanese delegation's remarks about subs - is likely to irk China, which fears such moves are aimed at containing the expansion of its power in Asia. That is particularly so when talk turns to three-way co-operation with the US.
Backing up Mr Ishikawa's remarks, senior Japanese naval officer Rear Admiral Naoto Sato, who is also part of the delegation visiting Australia this week, said that freedom of navigation at sea was a core value shared by Japan and Australia.
"If we had the same sister ships and submarines, we understand how we operate and the performance. We both know each other very well so we can effectively operate in this area," he said.
Freedom of movement on the seas is vital to Australia's export-driven economy, as well as to Asia's stellar growth. It has been a key theme at the Navy's Sea Power conference, with the head of the US Pacific Fleet Admiral Scott Swift and Defence Minister Marise Payne both stressing that any impediment to such freedom would have catastrophic effects on the region.
Concerns have been raised in the wake of Beijing's island-building in the South China Sea about any efforts by the regional giant to impede such freedom through key shipping lanes.
Hidehiro Ikematsu of Japan's Ministry of Defence stressed that Japan had no intention of trying to contain China.
"Let me be clear: Japan doesn't have any intention to contain or confront China. We don't want or expect Australia to make a choice. We simply want to strengthen ties with Australia regardless of other countries," he said.
Japan is offering to build Australia an evolved version of its Soryu class boat. Mr Ishikawa said Japan was conferring a special status on Australia by sharing its highly classified submarine technology, something it was unlikely to do with any other country.
Japan, like Germany and France, is offering to build all of the new submarines in Australia if that is what Canberra wants. It would build a mock-up boat first to iron out flaws, the delegation announced this week.
It would do most of the building at a refurbished ASC shipyard in Adelaide but could also deliver some work to Melbourne, Newcastle or Perth, said Noboru Flores from Mitsubishi Heavy Industries, which would build the submarines along with Kawasaki Shipbuilding Corporation.
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