President Reagan told Japanese Prime Minister Yasuhiro Nakasone yesterday of "mounting frustration" in the United States about lopsided trade between the two nations as Nakasone declared his commitment to a "historic change" in Japan that could bring fundamental improvements.

The views of the two men at a midday Camp David meeting, which was marked by gestures of unusual hospitality for a foreign leader, were conveyed by Japanese and American officials in separate briefings later in the day.

The "Ron-Yasu" relationship, as Nakasone has referred to his politically helpful personal rapport with the U.S. president, was furthered in several ways.

These included Reagan's willingness to meet Nakasone on a Sunday at his normally private Catoctin Mountain retreat, presentation of a presidential windbreaker to him, and an intimate luncheon attended only by the president, First Lady Nancy Reagan, Nakasone and an interpreter, while a dozen other officials, including Secretary of State George P. Shultz and Foreign Minister Shintaro Abe, lunched separately in another building.

Nakasone, who will host next month's Tokyo Economic Summit of seven industrialized nations, faces difficult odds in seeking to extend his leadership to an unprecedented third term as prime minister after this October.

He has taken an unusual degree of personal leadership in seeking to alleviate U.S. concern on trade issues as Japan's trade surplus with the world, and the rest of the world's trade deficit with Japan, have grown spectacularly.

According to Japanese officials, Reagan asked Nakasone yesterday to begin a new series of U.S.-Japan market-opening negotiations similar to those under way since January 1985 in telecommunications, electronics, forest products and medical equipment and pharmaceuticals.

Announcement of new areas to be covered in additional negotiations may be made this morning at the White House after a final Reagan-Nakasone session.

Yesterday, Reagan also requested further consultations between the two governments on semiconductors -- among the most contentious trade issues -- as well as tobacco and wine, Japanese officials said.

Accounts by U.S. and Japanese officials indicated that Nakasone presented no specific information about how he plans to implement an April 7 report by a blue-ribbon commission calling for basic reform of Japan's economic structure and trade with the rest of the world.

A senior U.S. official who briefed reporters at the White House Friday said said Reagan would be "very much interested in hearing Nakasone's views on implementation plans of this report," which employs very sweeping but very general language. After the Camp David meeting, the same official, who briefed under "background" rules barring use of his name, said no details had been given.

Nakasone told Reagan that he will "not necessarily follow" the blue-ribbon report in all respects, the U.S. briefer said. Nakasone "has other ideas not in the report" for tackling the trade frictions and imbalance between the two countries, he added, declining to be specific.

Reagan was "impressed by the determination and commitment" on the part of Nakasone to push basic reforms that would reduce Japan's trade imbalance, according to the White House briefing. The current U.S. trade deficit with Japan of $49.7 billion was described in the briefing as "unsustainable" over time.

Nakasone was quoted by Japanese officials as saying he realizes that huge trade surpluses piled up by the Japanese economy "cannot continue."

Despite seven separate packages of trade concessions offered to the United States during his administration, the U.S. trade deficit with Japan has tripled since Nakasone took office in November 1982.

Japanese briefers quoted Reagan and Shultz as saying there had been great improvement in economic relations since Nakasone's meeting with Reagan in Los Angeles in January 1985.

Another topic in the wide-ranging Camp David talks was the Philippines. Japanese officials quoted Nakasone as saying Japan is ready to assist the new government of President Corazon Aquino overcome severe economic difficulties.