Nakasone stars at party gathering, but a woman gets the applause

It was not exactly a party to end all parties. But if your hobby is politics, if you like to collect autographs from Cabinet ministers the way others collect them from rock stars, then the annual convention of Japan's Liberal Democratic Party is the place to go.

The prime minister himself is the chief attraction, both at the formal session in venerable Hibiya Hall and at the buffet lunch that follows in the garden of the prime minister's official residence. This year, as last year, Yasuhiro Nakasone is his name.

Like Ronald Reagan, he faces reelection this fall. It is a party election, not a national one, and his term is for two years, not four.

Because the Liberal Democrats are the ruling party, its president is automatically assured of the premiership. Mr. Nakasone has not yet officially declared his candidacy, but everyone assumes he will run again. If he is reelected, he will have ended a 12-year tradition of two-year premierships.

In his speech to the party faithful this year, the Prime Minister's main theme was the need for Japan to ''internationalize'' itself - that is, to become a more responsible member of the world community. Mr. Nakasone has repeated this theme ever since becoming prime minister a little more than a year ago.

Prime Minister Nakasone is a practised speaker, and he got a good hand from his audience, gathered from the far corners of this island nation.

But the really thunderous applause was reserved for a guest speaker, a trim lawyer in black suit and silver blouse named Kinko Sato. Mrs. Sato holds no office in the party, but she has had a distinguished career in jurisprudence, which is one of the most male-dominated professions in a still largely male-dominated society.

Mrs. Sato made no reference to the tiny number of women among Liberal-Democratic legislators, nor to the fact that factional rivalries have kept Mr. Nakasone from his cherished goal of appointing a woman to his Cabinet. (A handful of Liberal-Democratic women sit in the upper house, but none at all in the main seat of political power, the 511-seat House of Representatives.)

But her meaning was plain. After making everyone feel good by noting how, during the past several decades, the Liberal Democrats have evolved into a true national party, representing many divergent interest groups, she continued:

''The times are indeed difficult. But there is nothing to fear. The Liberal Democrats have a strong ally - women'' (laughter and applause).

''I hesitate to say this from the lectern, but I have a feeling that the gentlemen in the audience think that women are stupid, even though they may be too polite to say so openly'' (more laughter and applause).

''Well, women don't think they are stupid. In fact, they are not stupid. And if they were stupid, society would be in trouble.

''In the old days, women did all the heavy house work as well as bear and bring up children. Many were exhausted and died before their youngest child was fully grown.

''Today . . . women are overflowing with energy. They are full of vim and vigor. The Liberal Democratic Party cannot grow, nor can the country, unless it harnesses the abilities and enthusiasm of women. Remember, women outnumber men in our country, and they also outnumber men at the polls.''

That brought the house down. ''Oh, my,'' said a middle-aged, kimono-clad lady at the buffet that followed. ''Mrs. Sato said all the things I was thinking but didn't dare bring out into the open.''

And at the party, under a huge tent that covered nearly the whole of the Prime Minister's lawn, men and women alike vied to have their pictures taken with the outspoken Mrs. Sato.