“We think there are many other opportunities for defence cooperation, for instance in the area of helicopters and other defence equipment,” Cameron told the Yomiuri Shimbun newspaper in London ahead of the visit.
Britain is keen to become “Japan’s partner of choice” alongside Tokyo’s major ally the United States for defence industry collaboration, he separately told Kyodo News.
Cameron, who has headed Britain’s coalition government since May 2010, arrived at Tokyo’s Haneda airport shortly after noon (0300 GMT).
His two-day trip will include a brief meeting with Japanese Prime Minister Yoshihiko Noda and an audience with Emperor Akihito, before he goes on to a quick tour of Southeast Asia ending Friday.
Cameron is being accompanied by a delegation of British business leaders, including defence contractors eyeing joint development programmes with Japanese firms.
Noda is thought to be keen to forge a defence partnership with his British counterpart after Tokyo loosened its decades-old self-imposed ban on weapons exports.
The expected agreement would make Britain only the second country to have any kind of defence collaboration with Japan, after the United States.
The ban, lifted in December, had prevented Japanese firms from joining multinational weapons projects, other than with the United States, and left Tokyo with little choice in where it bought its hardware.
The easing of export restrictions means Japanese companies are now able to supply parts to foreign contractors, for example in Britain, who will be hoping to leverage their more advanced weaponry technology and sell finished products to Tokyo.
Japan in December chose to buy the US-developed F-35 stealth jet for its next-generation fighter over the Eurofighter Typhoon, in a deal that is estimated to be worth $4.7 billion.
Japan, whose industries took years to recover after World War II, declared in 1967 that it would tightly control its foreign weapons sales.
But China’s rise and East Asia’s changing security environment — as highlighted by the expected launch in the coming days of a North Korean rocket — have nudged policymakers into the change.
Cameron will also visit the headquarters of Nissan Motors, which recently decided to build a new hatchback compact car in Britain, in a 125 million pound ($200 million) investment, aided by a 9.3 million pound grant from London.
The new vehicle, called “Invitation”, will be built at Nissan’s Sunderland plant in northeast England from mid-2013.