Imperial family

Japan's imperial family, the only imperial family in the world today, is also one of the oldest royal lineages in the world, purportedly dating back to Emperor Jimmu in 660 BC, and known to be at least a millennium and a half old. Like many other royal families, the Imperial lineage is the product of centuries upon centuries of slow but definite inbreeding, to the point where the Imperial bloodline has been in danger of halting altogether.

The current problem is that no new male heirs are being born into the family: the youngest male in the family, Prince Fumihito, is now 37 years old, despite the fact that girls have been popping out left and right. While there *have* been female emperors in Japan before (see Emperors of Japan for a full list), there have been none in modern times (i.e. after the Meiji Restoration), and the officials inside the Imperial Palace have shown little willingness to change. See Japanese Imperial Succession for more on this problem.

The current official Imperial family is descended from Emperor Meiji and his first concubine, Yanagiwara Naruko (1855 - 1943). With deceased links italicized, it looks like this:

• Harunomiya Yoshihito, Emperor Taisho (1879 - 1926)
  married Kujo Sadako, Empress Teimei (1884 - 1951) in 1900
  • Michinomiya Hirohito, Emperor Showa (1901 - 1989)
    married Kuni Nagako, Empress Kojun (1903 - 2000) in 1924
    • Terunomiya Shigeko, Princess Shigeko (1925 - 1961)
      married Higashikuni Morihiro (1911 - 1969) in 1943
    • Hisanomiya Shichiko, Princess Hisa (1927 - 1928)
    • Takanomiya Kazuko, Princess Taka (1929 - 1989)
      married Takatsukasa Toshimichi (1923 - 1966) in 1950
    • Yorinomiya Atsuko, Princess Yori (1931 - ?)
      married Ikeda Takamasa (1929 - ?)
    • Tsugunomiya Akihito, Emperor of Japan (1933 - )
      married Shoda Michiko, Empress Michiko (1934 - ) in 1959
      • Hironomiya Naruhito, Crown Prince Naruhito (1960 - )
        married Owada Masako, Princess Masako (1963 - ) in 1993
        • Toshinomiya Aiko, Princess Aiko (2001 - )
      • Akishinonomiya Fumihito, Prince Akishino (1965 - )
        married Kawashima Kiko (1966 - ) in 1990
        • Aya Mako, Princess Mako (1992 - )
        • Aya Kako, Princess Kako (1995 - )
      • Norinomiya Sayako, Princess Nori (1969 - )
    • Hitachinomiya Masahito, Prince Hitachi (1935 - )
      married Tsugaru Hanako (1940 - )
    • Suganomiya Takako, Princess Suga (1939 - ?)
      married Shimazu Hisanaga (1934 - ?)
  • Chichibunomiya Yasuhito, Prince Chichibu (1903 - 1953)
    married Matsudaira Setsuko (1909 - 1995)
  • Takamatsunomiya Nobuhito, Prince Takamatsu (1905 - 1987)
    married Tokugawa Kikuko (Princess Takamatsu, 1911 - ) in 1930
  • Mikasanomiya Takahito, Prince Mikasa (1915 - )
    married Takagi Yuriko (1923 - ) in 1941
    • Mikasa Yasuko, Princess Yasuko (1944 - )
    • Mikasanomiya Tomohito, Prince Mikasa Tomohito (1946 - )
      married Aso Nobuko (1955 - ) in 1980
    • Katsuranomiya Yoshihito, Prince Katsura (1948 - )
    • Mikasa Masako, Princess Masako until 1983 (1949 - )
      married Sen Masayuki (1956 - ) in 1983
    • Takamadonomiya Norihito, Prince Takamado (1950 - 2002)
      married Tottori Hisako (1953 - ) in 1984
      • Takamadonomiya Tsuguko, Princess Tsuguko (1986 - )
      • Takamadonomiya Noriko, Princess Noriko (1988 - )
      • Takamadonomiya Ayako, Princess Ayako (1991 - )

Until the end of World War II, another branch of the imperial family was recognized as well. Meiji's other concubine, Sono Sachiko (1867 - 1947), bore him four daughters (Masako, Fusako, Nobuko, and Toshiko), all of whom married into noble miyake families descended from Fushimi Kunie (Taisho and Hirohito also married into this family). This led to several members of the imperial family marrying their cousins: it's not too surprising, then, that members of the miyake have been commoners since 1947.

How to address the Imperial Family (from http://www.geocities.com/jtaliaferro.geo)

The Emperor (Tennō), the Empress (Kogō), the Empress Dowager (Kōtaigo, literally the emperor's mother), and the Grand Empress Dowager (Tai Kōtaigo, literally the emperor's grandmother) are styled His or Her Imperial Majesty (Heika). Imperial princes (Shinnō) and their consorts (Shinnō-hi), imperial princesses (Naishinnō), princes of the blood (ō) and their consorts (ō-hi), and princesses of the blood (Nyoō) are styled His or Her Imperial Highness (Hidenka).