The emperor's daughter is clad simply in a white dress with diagonal blue stripes. The only jewelry is a plain gold locket on a chain around her neck.

Her family has ruled Japan -- and been the object of religious ritual -- for nearly 3,000 years. Yet there is a brief, awkward moment as she sits down to chat with an American visitor. What do the unwritten laws of politeness and deference require? Both parties stand diffidently in front of their chairs until a translator suggests, "Won't you sit down?" and then both bodies descend to the chairs in perfect synchronization.

The princess is 50ish, with just a few strands of gray showing near the temples in her jet-black hair. She sits almost like a statue, the hands immobile in front of her, the face serene but almost never smiling. She gestures seldom; when she does, it has a special impact.

"She speaks English," one is assured, but the only English word she actually uses during a half-hour converstion is "yes" -- a word that can get you into trouble in Washington.

"Are you enjoying your visit to Washington, Your Highness?"

"Yes."

"I am very pleased to meet you, Your Highness."

"Yes."

The princess is addressed as "Your Highness," but her name is Atsuko Ikeda. Her husband is a member of the traditional nobility, a count, and no relation to Hayato Ikeda, who was the prime minister of Japan in the early '60s and one of the chief architects of Japan's spectacular postwar recovery.

Her personal name ends, as do the names of many Japanese women, with the suffix "ko" which means "child." ("Ko" attached to a word designates the status of a child: An "onna" is a woman, and "onnano-ko" a girl.)

She is an ardent supporter of women's rights in a country where this is still a new idea.

Last week in Washington, at the 45th international convention of Zonta, the women's organization, she carried her nation's flag in a public procession that included the flags of 46 other nations, and she was the center of attention. Nobody in her family had ever done anything like this before. It was also a revolutionary development that she came to Washington almost alone, with just one chaperone rather than an entourage. The Family

She is very quiet, self-contained, exquisitely polite in this foreign country whose etiquette is not necessarily her own. Formal poise is an imperial tradition: Her family is a public institution, though its members almost never appear in public.

Her father, Emperor Hirohito, has been the emperor of Japan since Christmas Day in 1926, which was not called Christmas Day in Japan, where Hirohito was venerated as a god. He is still regarded as such by some of his people, but a readjustment of image began on Aug. 15, 1945, when he broadcast the announcment of Japan's surrender in World War II.

Now, he is the head of a constitutional monarchy. His oldest son, Crown Prince Akihito, is married to a commoner, Michiko Shoda. But he remains, according to tradition, the 124th lineal descendant of the first emperor, Jimmu Tenno, who led a migration from the West in the seventh century B.C. and established his capital at Yamato. The People

Visiting a country where she can see people everywhere driving Japanese cars, watching television on Japanese sets, listening to Japanese transistors and taking pictures with Japanese cameras, her reaction is: Where is all the Coca Cola? "In Japan," she says, "we have a Coca Cola machine every 50 feet. I have not seen a Coca Cola machine since I have been here." A princess leads a sheltered life, particularly when traveling abroad.

As for the products of Japanese technology all over the American landscape, she stops to think for a long moment before saying:

"It is your know-how. The Americans taught us how after the war. The Japanese have to make a living by working hard. We have no natural resources, only our brains. We are very grateful to the United States, and we wish to maintain friendly relations in the future."

What has America given to Japan beyond Coca Cola? Well, the emperor's daughter says, there are soybeans. "On my table at home is a bottle of soy sauce made with American soybeans. My tofu [bean curd -- a staple in the Japanese diet] -- is made with American soybeans. We have ketchup from the United States . . . blue jeans . . . chewing gum . . ." The Zoo

When the princess married her noble suitor 27 years ago, they chose a lifetime project on which they would work together. Both being interested in zoology, they decided to start a zoo.

"I had a large plot of land," she explains, "and we decided to use it for a zoo for children. Children need much happiness. Last year was the Year of the Child -- but we started long before."

The Ikedas are childless. "I have no children," she says, "so I share my life with the animals."

She remembers her own childhood as "very happy."

Very protected, too. The protection (and the restraints that go with it) may be slightly attenuated, but traces remain. "My younger brother, the crown prince, sent me a beautiful farewell gift and a message, 'Please have a nice trip to the U.S.A.,'" she says. "But my husband was very worried to see me traveling alone." Women and War

Atsuko Ikeda came to Washington specifically for the convention of Zonta, a service organization for women in executive positions. It began in the United States as a group working for women's suffrage and decided to keep on going after that battle was won.

"I was asked to enter the club to promote social welfare," the princess says, "and I find it very interesting. I shall do my part in helping people. sI am particularly interested in the position of women. We wish to take our part in the advancement of society as a whole.

"Long ago, women were very far behind men -- but now, we are becoming educated. And with equality of the sexes, we are able to promote ourselves as human beings. We are promoting world peace.

"I think that women are more interested in peace, while men are often more interested in war."