'Leaders in both Japan and China know it would not be wise to quarrel. Healthy competition is good, but they know it should not be a zero-sum game.' University of Tokyo professor Akio Takahara on the future of Sino-Japanese relations Japan's Prime Minister, Yukio Hatoyama, has to think about how to treat the country's neighbours. Leaders from China, Japan and South Korea met in Beijing at the weekend. They talked about trade. Hatoyama also wanted to form an East Asia group like the European Union. Takahara said leaders in Japan and China know it 'would not be wise to quarrel' because Japan needs trade and China is a big part of trade. China is wary of Japan because of the second world war. Former Japanese prime ministers made things worse by going to a shrine which honours war criminals. Some experts say China will become the second biggest market in a year. Japan is now the second biggest market behind the US. Takahara said their rivalry should not be a 'zero-sum' game. Zero-sum is when a gain by one side must be matched by a loss by another side. For example if Japan gets stronger China gets weaker. He believes the two countries will benefit working hand in hand. China is Japan's biggest trading partner and second largest export target.