Tokyo — Ten years after the opening of Japan's embassy in Peking, euphoria has given way to more businesslike dealings in relations between the two East Asian neighbors.
In meetings with Chairman Deng Xiaoping, General Secretary Hu Yaobang, and Premier Zhao Ziyang, Japan's Prime Minister Zenko Suzuki has pledged and repledged that his country will never again take the path of militarism.
And in a speech to a Chinese audience in the Chinese capital Sept. 29, Mr. Suzuki said, ''The grand project - a millennium of Sino-Japan friendship - has only just begun.''
Although cordial and warm in their responses, the Chinese leaders have said in effect that they believe Mr. Suzuki's sincerity, but have lingering doubts about militaristic tendencies among a portion of the Japanese people.
Meanwhile Sino-Japanese trade has registered a sharp decline in Japanese exports this year, although trade has increased tenfold in the 10 years since the opening of diplomatic relations. Total trade turnover may not go beyond $9 billion this year, one expert in the field warns.
(Sino-Japanese trade increased from $1.1 billion overall in 1972 to $10.3 billion in 1981. From January to July of this year, Japan's exports to China totaled $2 billion, a decline of 36.8 percent over the same period the year before. Japan's imports from China during the same period were $3.1 billion, or 13 percent more than the previous year.)
Trade, politics, emotions aroused by Japan's 1937 invasion of China, and cultural memories of a shared civilization interact in complicated ways in the Sino-Japanese relationship.
''To us, China can never be just another country,'' says a high-ranking Japanese diplomat. He means that in dealing with China, Japan can never ignore either past history or the geographical fact of 1 billion continental people neighboring 100 million islanders.
But in the dining rooms of the Peking hotels, many exasperated Japanese businessmen, fresh from long negotiating sessions with Chinese counterparts, disagree. They feel they are paying through the nose for the privilege of doing business with China. They see little evidence of the ''equality and mutual benefit'' constantly being preached at them, and heartily wish they could treat China as ''just another country.'' Many of them belong to the postwar generation and feel no personal guilt for Japanese wartime actions.
Mr. Suzuki belongs to an older generation. He may not be a particularly forceful prime minister, but he does have strong convictions on the subject of war and peace, having started out his political career as a socialist.
The Chinese leaders seem to have accepted his sincerity when he told them that the Japanese people had decided that they must ''never again repeat such actions'' (as the invasion of China) and that they had therefore enacted a ''peace constitution under which Japan cannot become a big military power again.''
People of Deng's and Zhao's generation have memories of the long guerrilla campaign against occupying Japanese forces that probably can never fade. The leadership used the textbook controversy with Japan as a means of reminding their own postwar generation of the kind of sacrifices their fathers underwent for China to be free of foreign invaders.
(The textbook controversy arose this summer when the Japanese Ministry of Education ordered the revision of a number of history textbooks describing the Japanese invasion of China as an ''aggression.'' It was settled a week before Mr. Suzuki's current visit to China, when Peking accepted the Japanese government's promise to change the offending textbooks.)
At the same time, Chinese fascination with Japanese technical prowess continues. Hu was probably being more than just polite when he said he would like to visit Mr. Suzuki's country to ''learn'' from Japanese experiences.
If the Chinese could energize their workers to have the same sense of dedication and to maintain the same rigid quality standards that Japanese workers take for granted, China would be well on its way to fulfilling the leadership's promise of a fourfold increase in production by the end of this century.
There is also continuing Japanese fascination with China's vastness and the sweep of its millennial civilization. Planeload after planeload of tourists disembark at Peking airport, shuffle across the echoing courtyards of the Forbidden City, peer across the windswept battlements of the Great Wall, and then wander across China to relive Emperor Xuanzong's love affair with the Lady Yang amid the now vanished imperial splendors of Changan (present-day Xian), or to exclaim over the fantastic landscapes of Guilin.
China's relationship with Japan is different from that with the United States. China is at the same time closer to Japan, yet further apart, than it is to the United States. Both relationships, however, are vital to the interests not only of the two partners concerned, but also of the Western world as a whole.