As the crown prince and princess approach their third wedding anniversary, Japan is whispering:

"I bet it's her problem; she was a working woman for a long time. The stress did it," says one middle-aged woman.

"Are you kidding? The emperor's brother had no kids either. That side of the family has had baby problems before. It's the prince," another says confidently.

And so on. Since June 9, 1993 -- the day Masako Owada, a Harvard-educated former diplomat, ended her career and accepted life inside the cloistered walls of the Imperial Palace -- the princess has had one crucial job: produce an heir. A male one. On her wedding day, Princess Masako donned a 12-layer, 30-pound silk kimono, consistent with the style worn by the imperial family for 1,200 years, and, with her husband, prayed at a palace shrine for a son.

Now, though Princess Masako is only 32, people are abuzz because there is still no sign of an answer to that prayer. At risk is the longest continuous family dynasty on Earth. The current emperor is said to be the 125th direct descendant of a monarchy that stretches back 2,600 years to Amaterasu, the Sun Goddess.

Pressure? What pressure?

Women's magazines beg the princess to relax. "Don't be beaten by the pressure of pregnancy!" advises a Ladies' Own cover. "Infertility treatment! The moment of truth after three years!" screams Weekly Woman. Television variety shows speculate on the hold-up.

Goldfish make babies with more privacy.

Because no little bundle of princely joy has arrived at the palace yet, what was once unthinkable in this male-dominated country is now voiced publicly: Will Japan be forced to allow a woman to ascend to the throne? In the last 2 1/2 millennia, there have been eight female emperors here (many women have been empress, a title that refers strictly to the emperor's wife). The last female emperor's reign ended in 1770 and the law now forbids a woman to be the symbolic head of Japan.

Attention has begun to focus on 4-year-old Mako, the crown prince's niece, as a possible future emperor, requiring a change in the law.

Time, of course, has not run out. An emperor reigns for life, and the hoped-for heir would be third in line. Reigning Emperor Akihito is 62. His son -- Masako's husband -- is Crown Prince Naruhito, 36.

Still, gossip about a childless crown prince and princess grows louder almost daily, and Princess Masako, the most popular woman in Japan, grows increasingly invisible. This brilliant former trade expert, who negotiated semiconductor agreements with the United States as a member of the elite Foreign Ministry; this charmer who speaks exceptional Japanese, English and French, and good German, Spanish and Russian; this magna cum laude Harvard graduate who wrote her thesis on "External Adjustments to Import Price Shocks: Oil in Japanese Trade" before entering Oxford University; this once thoroughly modern woman is now perhaps the world's most talented ornament.

She makes brief public appearances, but almost always with her husband and she rarely says a word. A recent 25-minute appearance at a celebration of the 50th anniversary of the Fulbright scholarship program was typical: The press was ordered not to ask any questions, and the royal couple said nothing.

A much-hoped-for news conference on the princess's birthday on Dec. 9 never materialized; instead, she answered questions by letter. Masako has spoken so few public words in the last year that people don't even remember what her voice sounds like.

"It's very odd; you never hear her voice," said Toshiaki Kawahara, an imperial watcher who has written widely on the subject of the Chrysanthemum Throne. "Many people are talking about it, wondering if we are going backwards . . . if the family is more locked up."

If so, the jailer is the Imperial Household Agency, a 1,200-person-strong department that runs the affairs of the royal family. The IHA oversees Masako's every appearance beyond the walls of the East Palace. In an interview there, Tsuyoshi Soga, the palace's chief chamberlain, was asked about the delicate baby question. "I really wish the Japanese media would be more sensitive on this point," he answered.

But he offered the following unsolicited testimony, apparently concerned that the lack of offspring might spark gossip that the prince and princess do not get along: "I want to be frank. I have a lot of chance to see them together. They show their affection so openly it makes me blush. Their love is so expressive."

Soga, an elegant man in the palace uniform of black tails, spoke in a small receiving room. A silver tray engraved with the imperial family's chrysanthemum emblem held 35 short cigarettes. Eight beige, armless chairs and a painting of Mount Fuji were about the only other items in the room. But further inside the 20-room palace, there are lofty ceilings, grand hallways, ancient Japanese screens and porcelain, and the thick carpeting that hints at royalty. Though 100 people work there, the place seemed strangely silent. This is where Masako spends her days.

Sometimes foreign dignitaries call, but staff members can't recall any overnight guests, even family or friends. Masako spends hours learning ancient court rituals and the art of waka, Japanese poetry. Outside her doorstep, but inside the walls, are a well-hidden swimming pool, two tennis courts and two mountain bikes for pedaling around the forested grounds. When Masako leaves home, she always rides in the back seat of a chauffeur-driven black sedan, always to the left of her husband.

Masako keeps in touch with only a very few close friends who protect her completely and say she is enjoying her role as future empress. But her life is not her own. Her cooks prepare a weekly menu and do not deviate from it. She can't wear a bathing suit at the beach because of prying photographers. She shops through catalogues and from designers who come to her -- but unlike the British royals, who dash off to ski in Switzerland or to sun in Barbados, the Japanese imperial family has no money of its own. Her family makes all trips at the will of the government.

"In principle they are penniless," said Toshiya Matsuzaki, a senior reporter for Ladies' Own weekly magazine, which frequently writes about the imperial family. "They have no freedom, they can't do anything without government approval."

At the end of February, on Crown Prince Naruhito's 36th birthday, he and his wife appeared at a news conference where the prince addressed the ever-lurking baby question. "I heard you all would like to know about the attitude of the stork," he said. "It seems the stork needs a quiet environment. . . . If the stork is to fly that will be strictly decided by the stork's pace."

Masako made no comment and showed no reaction.

Compare that with their first joint news conference in 1993, where the bubbly pair announced their engagement. After that event, conservatives criticized Masako for speaking 39 seconds longer than her husband-to-be. Traditionalists were not pleased that she used the words, "But if I may be allowed to add . . . ." Women, these critics maintained, are designed to multiply, not to add.

Masako was following up on the crown prince's statement that he wanted a family "blessed with peace and cheer." Masako added that she hoped for a "warm family full of love that helps each other in difficult times." She even told reporters that she teased the prince, who plays the violin, that she hoped he didn't want enough children to fill out an orchestra.

Masako's shielded life -- so different from the one she led while living in Boston, New York, Moscow and Oxford -- has many speculating about her happiness.

Junko Kawai, a 30-year-old professional woman in Tokyo, said she feels sorry for the princess. "She is so very intelligent . . . and I have noticed her voice is not heard anymore. . . . I am sorry for her because it has become almost like her duty to produce a male heir. Ordinary women don't like to be always asked, When are you going to have a baby?' " All of this is, perhaps, the inevitable fallout from the clash of old and new. Before World War II, Japanese emperors held vast land and wealth and were worshiped as gods. The U.S. occupation force that ruled Japan after the war changed all that. Today, though a small, ultraconservative element in Japanese society still reveres the royals as superhuman, the mainstream view is that the Chrysanthemum Throne is symbolic, unifying, charming and harmless.

"Before World War II, older people knelt on straw mats along the road and bowed in worship when the emperor rode by. They were never to lift their heads to look at him. Today they stand and clap and yell Your Majesty!' " Matsuzaki said. "Sometimes the emperor is even asked to shake hands. For the elderly, this is an unbelievable change."

Makoto Watanabe, a top IHA official who speaks impeccable British-tinged English, disputes the suggestion that Masako has disappeared behind a chrysanthemum curtain. He said her public comments have been limited because the "roles of the royal family and the crown princess, as well as Masako herself, are in transition."

Masako may speak more in time, Watanabe said, perhaps when she is more comfortable with the change from "what she was before she got married, to what future role she might have. She is trying to adapt to her new life.

"The life of the Imperial Palace," he added, "is quite different from the life of ordinary people." Special correspondent Shigehiko Togo contributed to this report. CAPTION: Crown Prince Naruhito and Princess Masako are under tremendous pressure to produce an heir: The current emperor is said to be the 125th direct descendant of a monarchy that stretches back 2,600 years.