From Reuters:

A man attacked the car carrying the Japanese ambassador in Beijing on Monday and ripped off the Japanese flag flying on the vehicle, Japan’s Kyodo news agency reported, amid escalating tensions that led to the biggest anti-Japan protests in years.

Kyodo, quoting Japanese embassy officials in Beijing, gave no further details of the attack, but said the ambassador, Uichiro Niwa, was unhurt. The report said the embassy had “filed a strong protest with the Chinese Foreign Ministry”.