In Japan, Prime Minister Yasuhiro Nakasone is considered a politician with a difference. That has both complimentary and uncomplimentary connotations. On the uncomplimentary side, Nakasone's opponents sometimes refer to him as a "weathervane," charging that he shifts positions according to the prevailing political winds.

On the complimentary side, his supporters point out that he has staked out a more positive, even aggressive, role for Japan in international affairs, which accords Japan some of the respect it deserves within the Western alliance.

Pointedly, this most influential Oriental leader included himself and his country as part of "the Western camp" as he talked during an interview here last week of the upcoming Reagan-Gorbachev summit, and of his own new approaches to a more fruitful relationship with the Soviet Union.

There was a time when Japanese prime ministers concentrated on avoiding attention at international conferences: The less conspicuous they could be, the better. Not Nakasone, who is as adept as Maragaret Thatcher at elbowing his way next to President Reagan at picture-taking sessions during economic summits.

Moreover, although his command of English is far from perfect, he is the first Japanese prime minister willing to use the language to a considerable extent with fellow heads of state, which makes it easier for foreigners, who, of course, almost never take the trouble to learn Japanese.

During an interview, Nakasone abandoned Japanese formalities, and got down to shirt sleeves in an uncomfortably warm Waldorf Astoria Towers hotel room. And overriding a press aide's warning to me to stick only to social chatter or "light" issues during a preinterview luncheon, Nakasone immediately invited questions about the Reagan-Gorbachev summit and volunteered that "on the record is okay."

For all of these reasons, Nakasone is considered the Japanese politician most like American politicians. Is this a fair comparison? I asked him. He answered in English: "Yes, I think so. My way of talking is somehow like the American way."

As is well known, Nakasone and Reagan have established a close "Ron and Yasu" relationship. This has stood Nakasone well in Japan, a country that dotes on everything American, despite the current unpleasantness over Japan's embarrassingly large trade surplus with this country.

How did that "Ron and Yasu" relationship spring up? Nakasone's response was -- this time through an interpreter -- "We had the same vibes."

Nakasone went on to explain that the reason he admires Reagan so much is that the president reminds him of John Wayne. And so it becomes clear that Nakasone sees not only Reagan, but himself, as exemplifying the decisiveness of the heroic movie character.

Over lunch, Nakasone recalled that after the war, he had favored a presidential rather than a parliamentary form of government for Japan, so that its citizens could enjoy the direct election of their chief of state. "That would make politics meet the needs of the people," he said.

Nonetheless, although the parliamentary form of government was chosen -- in part so there would be no rival to the emperor -- Nakasone said that he conducts business "by appealing directly to the people" because that is the best way of serving their needs. "I am doing things now just like the American system, even though . . . I am getting some jealousy from some factions in my party," he said.

Most recently, Nakasone has been appealing to Japanese citizens to put aside their reluctance to buy imported goods. He conceded that the huge Japanese trade surplus with the United States -- even if the cause is more an overvalued dollar than Japanese trade barriers -- has climbed to an unsustainable level.

So after years of clinging to a philosophy of "export or die," Nakasone is trying to bring Japan -- slowly, to be sure -- into a new stage of development in which imports are another crucial element. This, he said, will force Japan "to change the economic and social fabric or structure so that it will be a harmonious one with the world." Antiquated systems of distribution and other impediments to imports will have to be whittled away.

It won't be easy: In the first place, the Japanese instinct is to save rather than spend. The current savings rate is an incredible 17 percent of disposable income compared with an all-time-low 2 percent here. That means that there is a low personal standard of living in Japan compared with the nation's industrial wealth and power, as people put money away for their children's education and their own old-age needs.

And when the typical Japanese family does spend money on consumer goods, it prefers Japanese products, which they believe to be of higher quality than imported goods.

Nakasone, who became prime minister in 1982, is finishing a second term that is scheduled to end in November 1986. Under the current rules of his Liberal Democratic Party, there is a two-term limit. But such rules can be changed. Smilingly, he doesn't want to talk about "this delicate question," which is one of the hottest in Japan at the moment. "I am not a dictator," he laughed.

Whether Nakasone is successful in extending his stewardship in Japan will depend a great deal on how well he is able to defuse the tense trade issue with his trading partners here, in Europe and in Asia. Some political opponents in Japan label him too pro-American, too ready to jump at "Ron's" bidding. But Nakasone has played his version of the John Wayne image well with the average citizen, who has come a long way from the poverty of the first postwar years, and doesn't mind at all seeing Nakasone show the Japanese flag in world capitals when summit leaders meet.