WHEN Princess Kiko, second daughter-in-law of Emperor Akihito, became pregnant last January, it seemed like an answered prayer. Hopes were high that, at last, the world’s oldest hereditary monarchy would have a male heir.

On Wednesday, after months of speculation, the question will finally be settled when Princess Kiko will give birth by Caesarean section.

But courtiers are now worried that even the arrival of a male heir may not guarantee the long-term survival of the Imperial family.

To ensure the continuation of the 2,000-year-old Chrysanthemum throne, senior members of the Imperial Household Agency (IHA) are discussing changes to the law to ensure that, if necessary at some time in the future, a woman could reign as empress.

But there is powerful opposition from the country’s ultra-nationalist right wing, which has already physically threatened Imperial courtiers.

Before the announcement of the Princess’s pregnancy, the government of Junichiro Koizumi was pressing ahead with legislation to allow a woman to succeed to the throne. Polls suggested that more than two-thirds of Japanese people supported the idea, but it was vociferously opposed by a minority of conservative politicians and by Japan’s sometimes violent ultra-loyalists who refuse to contemplate any divergence from tradition.

The threat was brought home when the Emperor’s Grand Steward, Shingo Haketa, was threatened by a Right-winger who lingered around his house and handed him a menacing letter as he was commuting by train from home to the Palace. “The Emperor may not share their views, but the truth is that these are the people who love the Imperial family the most,” a source close to the Palace told The Times. “The IHA cannot afford to alienate them.”

The crisis goes back to 1993 when an Oxford-educated career diplomat married Emperor Akihito’s oldest son, Crown Prince Naruhito, and became Crown Princess Masako. Their daughter Aiko was born in 2001.

Since 2003, Masako has been treated for depression which has left her unable to perform public duties and palace officials do not expect her to have another child.

The Crown Prince’s 40-year-old younger brother, Akishino, is next in line, but both his children are also girls. So there was a strong reaction when the news leaked last winter that Akishino’s 39-year old wife, Kiko, was pregnant.

The political moves to allow a woman to reign were immediately dropped. Although the palace insists that they do not know the baby’s sex, there has been widespread speculation in Japan’s weekly magazines that it is a boy.

But, according to a source close to the palace, the birth of a son will only postpone, not solve, the problem.

“Even if it is a boy, he would end up being the only member of the Imperial Family, and that would be intolerable,” the source told The Times. “To put it very bluntly, you need to have reserves.”

The widely opposed compromise is to allow imperial princesses who marry commoners to retain their royal status so that their future sons could take their place as “reserves” in the order of succession.

The idea would have to be approved by the Japanese Diet, and is not likely to be put forward until well after the birth of Princess Kiko’s child.

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