WASHINGTON (AP) _ It was inevitable that Japanese Prime Minister Noboru Takeshita would be asked during his get-acquainted call on the new Bush administration whether he addressed the U.S. president by his first name.

Each new prime minister of Japan generally visits Washington early in his term to demonstrate to the Japanese public that he will have good relations with his country's big trans-Pacific ally.

Yasuhiro Nakasone, prime minister in 1982-87, set a new standard by proclaiming his vibrations with President Ronald Reagan so positive that they called each other ''Ron and Yasu,'' American style.

Nakasone's successor, Takeshita, met that challenge a year ago when he was able to announce here that he had cultivated a ''Ron-Nobu'' first-name relationship with Reagan.

And Takeshita happily told a Japanese embassy gathering here Thursday that he and ''George'' had decided to use first names. He added that he hopes they can have casual telephone exchanges and told reporters he was impressed by Bush's character and intelligence.

Bush, addressing Takeshita at the White House Thursday, referred to the late Japanese emperor not as Hirohito but as Emperor Showa. The president was using the Japanese style of referring to a former emperor by the name of his era.

The emperor, whose funeral Bush plans to attend Feb. 24 in Tokyo, died last month in the year Showa 63, which at the time was the Japanese calendar equivalent of 1989. The same year is now Heisei 1, using the name of the new era of Emperor Akihito. Showa means ''Enlightened Peace,'' Heisei, ''Peaceful Achievement.''

Takeshita told Bush the Japanese people were deeply moved by his decision to attend the state funeral.

A former schoolteacher, Takeshita recalled at lunch in the State Department's Benjamin Franklin Room that he was not very good at helping Japanese high school youngsters learn English, but he did teach them ''through Ben Franklin's writings, why America is so great and how Americans respect freedom, independence and diligence.''

''The spirit of the American Revolution, as represented by Franklin, is alive and well,'' he added.

Another Takeshita story was that he had stayed in Blair House, the U.S. presidential guest residence, 20 years ago as a 43-year-old aide to the late Prime Minister Eisaku Sato when Sato visited former President Richard Nixon. His boss suggested he should plan to stay in Blair House again on a future visit - meaning he should aim at becoming prime minister. It came true.

Takeshita and Secretary of State James Baker III reminisced about when they were their countries' respective finance ministers at the 1985 New York Plaza Hotel meeting that grappled with currency exchange rates.

Takeshita said currency rates ''should be decided by God and I agree with that,'' Baker, then U.S. Treasury secretary, recalled jokingly. One American dollar was then worth 245 Japanese yen but Takeshita and other finance ministers said it should be 215-220 yen, and ''two weeks later it became 215 yen,'' Baker said. Today, one dollar is worth in the range of 130 yen.

By coincidence finance ministers of the same seven ''G-7'' countries, accompanied by their staffs, met in Washington during Takeshita's latest visit. His last day here, he dropped in at their meeting for a brief round of handshakes with old acquaintances.

From Washington, Takeshita started home via Los Angeles, where he plans to meet his friend ''Ron'' Reagan Monday. A spokesman said it was in the tradition of Japanese etiquette that the prime minister should personally wish the retired president well and thank him for his leadership of the Western alliance.

Asked why it was necessary for the prime minister to wait through the weekend for Monday, spokesman Koichi Haraguchi said Reagan's schedule was such that ''they can meet only on Feb. 6.''