The birth of a girl to Crown Princess Masako in Tokyo yesterday means it now seems likely the constitution will be amended to allow a woman to ascend the Chrysanthemum throne, but the change will probably not be made for some time.
With the birth, all nine children born to the imperial family since 1969 are female.
Japan's royal family claims lineage back to the first emperor Jimmu (about 650 BC) and is the world's oldest hereditary monarchy. But it is ironic that a family that traces its roots back to a sun goddess, Amaterasu Omikam, cannot, as things stand, have a female monarch.
The lack of an heir increased pressure on the royal couple. Two years ago, the princess suffered a miscarriage amid a media frenzy.
Many people were concerned for her mental health in the tightly controlled, staid environs of the imperial household. The spontaneity she displayed in the early years of the marriage disappeared as she took on the role of a traditional wife, dressing conservatively and behaving demurely in Prince Naruhito's presence.
Questions about pregnancy at news conferences were initially laughed off with good humour but the responses from the crown prince became more terse over time.
