Congratulations are due to Japan's Princess Kiko, who, it was announced on Wednesday, is pregnant with her third child.
I'm sure she's happy, but must be dreading the political firestorm approaching.
What firestorm? Oh, uh, the imperial succession. You see, as the press here likes to phrase it, "No male heir to the throne has been born in forty years." In Japan, under current law, only men are allowed to sit on the throne. The current emperor has two sons, Crown Prince Naruhito (called "Kotaishi-sama" here; you never hear his name in Japanese) and Prince Akishino, who are 45 and 40, respectively. Naruhito and his wife, Princess Masako (a Harvard-educated commoner) have one daughter, Princess Aiko, who is four years old. Akishino and his wife, Princess Kiko, have two daughters who are both older than Aiko.
Under current law, the succession would go Naruhito, Akishino, then the current emperor's younger brother. After that, nothing.
So, since Aiko was born, there has been discussion of revising the imperial succession law to allow her to sit on the throne. The debate had been gathering momentum, with several possible proposals on the table. There are two issues -- the immediate successor to the throne, and the succession from that emperor/empress. For the immediate succession, there are two main options:
 Succession to oldest child, regardless of gender.
 Succession to oldest boy, if there are no boys, then succession to oldest girl.
For the following succession, there are two options:
[A] Succession to emperor/empress's children, regardless of gender of emperor/empress.
[B] Upon the death of an empress, succession reverts back to someone with an emperor on his/her father's side.
Under the 1/A combo, Aiko gets to be empress, and her children will follow her. Under the 1/B combo, Aiko sits first, then if she dies before her girl cousins, they will sit in order of age. When they are all gone, we're back to the current dilemma; the throne would potentially fall to some distant cousin (this would involve expanding the royal family to include more cousins).
Confused yet? Now it gets complicated. (Try drawing out some family trees and numbering them for different scenarios, just for fun.)
What if Kiko's child is a boy? Under current law, he would be third in line for the throne, after his uncle and father. Under the 1/B combo, he might never sit on the throne, but his children would in preference to Aiko's or even his sisters'.
Now, maybe to you, especially if you're, say, English, where things have been done another way for centuries, this might seem bizarre and byzantine. But not here.
Prime Minister Koizumi, who views himself as a reformer but often kowtows to the right wing, had supported a bill picking, I think, option 1/A. (There was a government-commissioned panel to investigate options that concluded a few months ago; I don't remember the details.) After Kiko-sama announced her pregnancy (or, more correctly, the Imperial Household Agency that controls her every movement announced it), Koizumi initially said he would press forward with the bill. But yesterday he backed off from that stance, saying the issue needs to be considered carefully; this is probably a prelude to shelving it at least until the gender of the baby is known.
There's more (including various interpretations of Japan's history with empresses, and a proposal by a distant cousin to revive the concubine system), but I'm out of steam. Google News will help you out if you want more.