Japanese Prime Minister Yasuhiro Nakasone seemed to feel some jokes were in order. First, as he sat next to Sen. John C. Danforth (R-Mo.), posing for photographers, he remarked in mock despair that on his trips abroad he hears complaints that all the cameras are Japanese these days.

Then, during a 90-minute session with Danforth and the five other U.S. senators who were calling at the prime minister's official residence in Tokyo Jan. 11, Nakasone expressed hope that Japan was not about to be struck by a "Danforth earthquake."

The idea was clearly to lighten the mood as Nakasone received a man whom many Japanese see as their country's chief enemy on Capitol Hill, the leader of a vicious protectionist movement that could wallop the country's export-driven economy.

Nothing incenses the Japanese more than talk that their trading practices are unfair and their right to sell in the United States may have to be restricted. Danforth, a tall, gravelly-voiced Episcopalian minister-turned-politician, has made a name in the Senate by doing both.

During his four-day visit, he argued hard in meetings with almost every important leader in Japan that the country must import more and reduce its $50 billion a year trade surplus with the United States. Otherwise, he said, Japan risks breaking down the world trading system that has made it prosperous.

He told them nothing they hadn't heard from countless congressional delegations that preceded him. But by some accounts, his standing and his force of delivery in telling of unemployment and the demise of public support for free trade in the United States packed a special punch.

His reputation has been a long time in the making here. Almost four years ago, readers of the Nihon Keizai Shimbun, Japan's equivalent of The Wall Street Journal, were given the following assessment of his standing at home:

In St. Louis, the newspaper reported, "there is a house that memorializes President Truman, who was a native of Missouri state. It is filled with visitors, we hear. Isn't that nostalgia for a man who bombed Japan in 1945 ? Today in Missouri, people's eyes are looking with expectation to a man whose image is a double of Truman's, John C. Danforth, 45, Republican senator, flag-carrier of reciprocity."

He is known here as the man whose automobile import bill forced the Japanese to put their own restrictions on car shipments in 1981. He is known as the man behind reciprocity, a concept by which Japanese access to the U.S. market would be curtailed if the U.S. decided its companies did not have equal access in Japan.

He is also remembered for his statement last year, as trade tensions between the two sides reached a new peak, that he would not receive any Japanese delegations. Refusal to keep talking, to try to find agreement, is a cardinal sin in this society.

Thus, it was no surprise that a Japanese TV reporter who interviewed Danforth briefly at Tokyo's Haneda Airport after his arrival informed him that Japanese find him "scary." He denied he was.

The next day, as Nakasone strode toward the room where Danforth was awaiting him, a reporter tagging along fired off the question: "This man's a hard-liner, what do you say to that?" Nakasone, always anxious to display his rapport with Americans, brushed it off: "No, no, it's not so. He's a friend of Japan."

Despite the buildup, Danforth's meetings with Japanese officials were generally cordial. Bunsei Sato, Minister of Posts and Telecommunications, reportedly gave him an imported Parker pen and said its quality was so high that he had bought 1,000 to distribute to his constituents. "I think they are surprised to find he doesn't have horns or a tail or a grimacing mask," said an aide traveling with the delegation.

Some Japanese said his statements here suggest he is not a true-blue protectionist at all. "What he was really saying was that he wants to sell more American products here," said Konoe Kawagishi, a former Washington correspondent for the mass-circulation newspaper Yomiuri Shimbun.

Danforth himself said the Japanese miss the point in focusing on him. He told the Foreign Correspondents Club of Japan: "Would that Japan's problem were only Jack Danforth. . . . Believe me, I am not an aberration, and by the standards of my constituents, I am not a hard-liner. The sad fact is this: In the United States, public support for free trade has collapsed."

In fact, many political and business leaders in Japan agree with his thesis that Japan must assume a new, more open stance toward the world economy and abandon its phobia of foreign goods. It is in how to accomplish that and to what degree that they part ways.

Danforth contends the problem is primarily a straightforward case of Japan being closed by a maze of formal and informal restrictions. His camp argues that forcing Japan to open up by clamping down on its access to the United States is only fair and should not be called protectionism.

The Japanese tend to blame exchange rates, lack of quality and service follow-up and poor marketing in Japan by foreign companies. Noting that Canada's huge surplus with the United States -- $20 billion -- has drawn little political fire from Washington, some suggest that feelings against Japan may be racially motivated.

From the start, Danforth seemed more intent on making his points than expanding his knowledge during what was only his second visit to one of the world's more complex countries. "I'm not going to go out to the highways and byways" to meet ordinary people, he said. "I wouldn't know how to do that." He also did not visit factories or businesses.

The trip brought no change in his views on the substance or solutions for U.S.-Japan trade problems, an aide said on his departure. But in a statement, Danforth concluded: "There was a remarkable meeting of minds on the problem and means of dealing with it. It remains to be seen if Japan's leaders can turn those intentions into action and results."

The Japanese press, meanwhile, was miffed that he never sat down with them for a substantive talk. A spokesman for the Japan Press Club, whose members cover the major media here, said it invited him to give a speech but was told that he was already booked to talk to the Foreign Correspondents Club.

"For a man who is so outspoken and critical of Japan, it is hard to understand why he did not choose the best, most conventional place to address the Japanese people directly," a Japanese newspaperman said.

At his appearance at the foreigners' club, a few Japanese applauded hostile questions. And a cartoon in the mass-circulation newspaper Yomiuri Shimbun gave him a not entirely sympathetic send-off. It showed him walking through a Tokyo shopping district at night weighed down with a newly purchased television, video recorder, personal computer and camera.

The caption read: "Danforth-san, please feel free to buy as many souvenirs as you like."