Hostility between Asia's two biggest economies is bubbling up again. But commercial logic is pulling in the other direction: Japan's economic success increasingly depends on China, and vice versa.
On September 3, geopolitics seems to be trumping economics. China's huge military parade to mark 70 years since the end of World War II is a well-timed nationalistic jamboree at a difficult juncture for the Chinese economy.
Meanwhile, Japan's military is seeking its biggest budget in 14 years, partly to reinforce its hold on uninhabited islands in the East China Sea - a claim hotly contested by Beijing. The Japanese economy, too, is struggling, as Prime Minister Shinzo Abe's battle against deflation falters.
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Investment is also perking up from the gloom of 2012, when disputes over the islands spawned anti-Japan riots in China. Earlier this year, trading house Itochu and Thailand's CP Group together bought more than a fifth of China's CITIC for $10.4 billion, the largest acquisition of a Chinese business by a Japanese investor.
However, a weak Chinese economy has seen Toyota delay a Lexus factory on the mainland. It's also clouding the outlook for trade between the two.
This has more than trebled since 2000. But Japan's annual exports to China have slumped more than 18 per cent since Abe came to power in 2012; trade the other way has fallen 10 per cent in dollar terms. Japan is also staying out of the Asian Infrastructure Investment Bank, which will finance Chinese President Xi Jinping's new China-centred trade network.
Of course, strong commercial ties don't prevent conflict - just ask Britain and Germany. But business people and tourists alike would probably rather see better relations between Asia's two big neighbours.
