"We still have scars in our hearts," said the Chinese factory worker, recalling the brutal Japanese occupation of northeast China more than 40 years ago.

As a boy of 10, the worker had gathered roots for firewood alongside a Japanese military road. A Japanese soldier cursed him and unleashed a dog that bit the boy and tore his clothes.

"They didn't consider the Chinese to be human beings. My only pair of trousers was torn to ribbons," said the worker, who referred to himself only as Zhu. "But what was the result of the war? They were defeated, and the Chinese nation still stands."

On the day of the Japanese surrender in 1945, he said, "People went crazy with happiness. The world turned upside down."

But now, Zhu, 54, and others speak of a new generation of Japanese who are considered friends. In interviews conducted recently in four cities in northeastern China, Chinese of all ages, including a number who had suffered under the Japanese occupation from 1931-1945, described relations with modern-day Japan as good. If there is lingering mistrust of the Japanese in this part of China, it is not immediately evident.

Given the bitterness of the past, China's friendship with today's Japan is remarkable.

In the northeastern region of China, once known in Japan and the West as Manchuria, where the Japanese occupiers were once the enemy, they are now the leading foreign traders, just as they are elsewhere in China. The Japanese have "conquered" the old Manchuria much more effectively with automobiles and television sets than they ever did with rifles and artillery.

A visitor to the former headquarters of the Japanese Imperial Army Regiment, which conducted germ warfare experiments on prisoners of war just south of the city of Harbin, travels to the site in a silver-gray car provided by the Chinese travel service and manufactured in Japan. It is a Toyota Crown deluxe. Along with other music, the driver plays a tape of a Japanese songs that have been translated into Chinese.

On the road, the Toyota passes other cars, trucks and minibuses made in Japan. Shen Baoji, who guides a visitor around the remnants of the germ warfare installations, carries a Canon Autoboy II camera made, of course, in Japan.

Shen said that every year a few hundred Japanese tourists come to this site. According to Chinese officials, more than 3,000 Chinese, Korean and Russian prisoners of war were killed with biological and gas weapons at the Harbin germ warfare factory.

In the coastal city of Dalian, Feng Renfu, a 62-year-old welder, recalled working in a shipyard for the Japanese and eating crushed acorns. No rice was allowed to the Chinese, he said. Dressed in rags, Feng was unable to afford even the simplest cotton clothes for protection against the harsh northeastern winter.

He said the Japanese overseers beat him several times "but not too seriously." They beat others more severely, with pickax handles, he said.

"I really hated the Japanese then, with a great hatred from the bottom of my heart," said Feng, speaking through an interpreter at a Dalian radio factory.

"But the Japanese who were responsible for the bitter suffering of the Chinese have been punished . . . . The younger generation of Japanese was not responsible for that."

Feng even had a good word to say for a few of the Japanese whom he encountered in the 1930s and '40s. "Not all the Japanese were bad," he said. "Some were kind even then."

In the truck-producing city of Changchun, chosen by the Japanese to be the capital of Manchuria, heavy military-style buildings of concrete and brick constructed by the Japanese weigh on the spirit. A Chinese museum contains several rooms filled with reminders of the occupation, including photographs of beheaded Chinese and drawings of a massacre scene.

At the very end of the exhibits, however, one suddenly comes upon a half a dozen color pictures of Chinese and Japanese leaders greeting each other and smiling.

Japanese diplomats have much better access to the Chinese leadership than do most other diplomats. The Japanese are close geographically, and they share cultural history with the Chinese.

China's top leaders, a number of whom spent a good part of their early lives fighting the Japanese, have decided to adopt a pragmatic attitude toward today's Japan.

But the new relationship is not without troubles. In candid moments, some Chinese complain that today's Japanese are only in China to make money through the sale of machinery, consumer goods and other products.

Increasingly, Chinese officials complain of a Japanese reluctance to invest in China and enter joint ventures with Chinese partners. The Japanese are considered extremely tough bargainers.

On the Japanese side, some businessmen complain that Chinese factories and workers are inefficient and produce much less than Japanese enterprises. Some doubt that China's economic modernization program can succeed.

"To do business with Japanese companies is not so easy," said Wu Disheng, the acting mayor of the industrial city of Shenyang. "The Japanese have not invested much in this area . . . . Japanese businessmen are not very farsighted."

"I have told Japanese friends that if you go on like this, you will lose the market, and you will be replaced by others," said Wu in an interview in his office, which is housed in a brick-and-concrete building constructed by the Japanese in the 1930s.

Reminders of the 1937-1945 war against Japan are evident everywhere in the Chinese media at the moment. Books describing the war are being issued to mark the 40th anniversary of the Aug. 15, 1945, Japanese surrender. The Chinese have produced a documentary film for the occasion and are building a museum near Peking's Marco Polo Bridge, where fighting erupted in 1937.

A senior Japanese diplomat in Peking, in the meantime, worries not about the past but about what he describes as the arrogance of some of today's Japanese visitors and of some of the Japanese businessmen working here.

While most Japanese visitors are well behaved, said the diplomat, some of the old soldiers who have returned here have, after a few drinks, taken to singing old war songs.

Also, some Japanese businessmen, he said, who once would have been intimidated by the idea of working in a Communist-led, highly structured country, have discovered that some of the Chinese are as interested in making money as they are. Since the Japanese had to work extremely hard to get where they are, they apparently feel a certain amount of contempt for those Chinese who now want to make money fast, the diplomat said.