Tei Hei is not having a good day. Huddled behind a table covered with mobile phones and stone hanko seals with carvings of the creatures of the zodiac, he admits business is "terrible".

That seems hard to believe: the pedestrianised roads at the heart of Yokohama's Chinatown - said to be the world's second biggest, with some 4,000 residents - are thronged with visitors on this Sunday evening.

But Tei Hei dismisses the impression of thriving trade with a backwards flick of his hand. "People might come here, but most of them only look in the shop windows; they don't buy things like they used to."

There is another factor at play that has made the bitter winds of Japanese winter even colder than usual, however.

Pressed, Tei Hei admits he knows of at least three occasions when the black-painted trucks favoured by Japan's nationalist groups have visited the district blaring martial music that harks back to the years when imperial Japan controlled large swathes of China. Their intrusions are motivated by the ongoing disputes over the East China Sea islands known in Japan as the Senkakus and in China as the Diaoyus.

Residents say the authorities managed to usher the interlopers away before they were able to provoke the confrontation they had been seeking.

The district, which can trace its history back 150 years, sprawls over 20 hectares a couple of blocks back from Yamashita Park and the seafront. It has outlived disasters both man-made and natural - including the Great Kanto Earthquake of 1923 - but the current row is taking its toll.

At the Kou Sei Wa restaurant, where plastic replicas of dishes ranging from Peking duck to whole lobsters and harumaki spring rolls take up the entire window display, the staff vastly outnumber the customers.

Next door, at the Kin Gen Rou food store, I admire a glossy photo on the wall behind the cash desk of a group of Japanese television stars hamming it up for the camera.

"They were [filming] here last week and it's good that they come because that should bring more people to Chinatown, after the show has been on television," the assistant says.

The show will go out shortly before Chinatown celebrates the Lunar New Year - a time when businesses here traditionally experience a jump in visitor numbers and earnings. But how takings will compare with those of last year - before the storm over the islands broke - remains to be seen.