According to the Japanese Constitution, the Emperor is the symbol of the Japanese state and the unity of the Japanese people. You could thus say it is symbolic that the Imperial household is now facing an unprecedented demographic crisis, one that may ultimately lead to a succession dilemma and possibly even a constitutional quandary. While the recent hospitalization of 78-year-old Emperor Akihito due to illness has probably made more people think about succession, a more urgent cause of official concern may lie elsewhere: marriage.

Japan's Imperial family currently consists of 23 members spanning four generations. The oldest, Prince Mikasa, was born in 1915 and is the youngest brother of the late Emperor Hirohito. The youngest is 5-year-old Prince Hisahito, Akihito's only grandson. Prince Hisahito has two older sisters (aged 16 and 20) and a famous cousin, 10-year-old Princess Aiko, the only child of Crown Prince Naruhito and his embattled wife, Princess Masako.

The Crown Prince has a brother, Prince Akishino (Hisahito's father), and five cousins, grandchildren of Prince Mikasa. All of these cousins are princesses and all are in their twenties except for one, who just turned 30. In other words, apart from Prince Hisahito, all of the young members of the Imperial family are females who are either of marriageable age or will be within a decade. Given that Princess Masako was born in 1963 and Princess Akishino (Hisahito's mother) in 1966, any further additions to the family would appear unlikely.