Sixty years after the end of World War II, historical resentments remain a persistent cloud over Japan-China relations. Japan says it has paid its dues for the past, in the 1951 San Francisco peace treaty and the 1972 joint communiqué in which China agreed to renounce demands for war reparations. It has issued high-level apologies on 17 occasions to China since.
But China says Japan has failed to repent sincerely for its wartime wrongs. It points to Japanese history textbooks that it says play down Japan's wartime wrongs, and to recent visits by the Japanese Prime Minister Junichiro Koizumi to the Yasukuni shrine to Japan's war dead. These have triggered demonstrations against Japanese interests in China, anti-Japan football hooliganism, and even attacks by hackers on Mr Koizumi's website.
The discovery in 2003 that 400 Japanese tourists had enjoyed a three-day sex orgy with 500 Chinese prostitutes - and on the anniversary of Japan's 1931 occupation of north-east China - stoked memories of Japanese abuses as colonial master and provoked outraged accusations that Japan was trying to "shame" China.
China experts point out that anti-Japanese demonstrations are one of the few forms of protest allowed in China.
Despite ever closer economic ties, it has been more than three years since the head of either country paid a visit to the other.
Countering the neighbours' deeply entrenched suspicions of each other may be difficult. There is little popular contact - particularly little Chinese tourism to Japan. And the media in both countries are often guilty of playing to popular national prejudices, analysts say.