Stone-throwing protesters have smashed windows at the Japanese embassy in the Chinese capital, Beijing, during a big rally against Japan's war-time past.
Protesters shouted slogans and burned a Japanese flag
Japanese-owned businesses also came under attack during the march, which thousands of protesters joined.
The protests come less than a week after China criticised Japan for approving new school books which it says gloss over Japanese atrocities.
Protests on this scale are very rare in China's tightly-regulated capital.
Correspondents say the fact that Saturday's demonstration took place signals tacit acceptance, if not approval, by the authorities.
The protest is the largest in Beijing since 1999, when thousands marched on the US embassy after Nato planes bombed China's embassy in Belgrade during the Kosovo war.
Japan's embassy in Beijing issued a warning to its nationals to avoid the protests and security was stepped up near the building.
Organisers spread the word of the rally on internet bulletin boards, which called for protesters to gather at a shopping centre in the north of the city.
Marchers chanted slogans and burned a Japanese flag, demanding a boycott of Japanese goods.
"Japan doesn't face up to its history," Cheng Lei said, quoted by Reuters news agency.
"We want to express our feelings so the Japanese government knows what we think."
Some smashed windows of a Japanese restaurant and others hurled bottles at a Japanese bank.
Hundreds of demonstrators threw rocks and bottles and shouted abuse at the residence of the Japanese ambassador to Beijing.
Another protester told AFP news agency earlier that the demonstration was a "patriotic rally".
"I am Chinese, I love China," Zhang Daili said.
"... [I]f you are a patriot then you must oppose Japan."
Public anger against Japan simmers very close to the surface in China, the BBC's Louisa Lim reports from Beijing.
Japanese businesses have been targeted by Chinese protesters
Many believe Japan has never apologised properly for its wartime atrocities, she says.
There has also been widespread Chinese unease at Japan's bid for a permanent seat on the United Nations Security Council, our correspondent adds.
More than 25 million people have signed an online petition against the move.
Recent protests in other Chinese cities have turned violent, with demonstrators scuffling with police.
China believes the newly approved Japanese school books underplay the country's military occupations of Asian countries in the first half of the 20th Century.
Tokyo says private companies, not the government, were responsible for the texts, and that it is up to individual school districts to decide which books they use.