A Duke or Prince is the highest of the five peerage ranks. It ranks above a marquis. It was used as a title for Lords in ancient China and for the peerage in Japan after the Meiji period. A Duke, which in English is said to be derived from the Latin word dux meaning a Roman General, or a Prince, the son of a member of the Royal Family, are equivalent titles for nobles in Europe and Russia. The Japanese peerage system was hereditary. Since the Japanese word 'Koshaku' is formally translated as Prince rather than Duke, Fumimaro KONOE, a statesman in the Showa Period, is sometimes mistakenly considered to be a member of the Imperial Family in Western documents.
Duke in Japan
In Japan the Peerage Law was enacted by the Imperial Household Ministry in 1884 after the Meiji Restoration, and Article 2 stipulated that the Kazoku (peerage) was divided into Gotoshaku or five ranks including Duke, Marquis, Count, Viscount and Baron, under which, a Duke ranked first. In 1889, when Imperial Edict No.11, Kizokuin (the House of Peers) Law was established, Article 1-1 of the edict entitled Dukes to be members of the House of Peers. In 1907, Koshitsu-rei (the Imperial Families' Act) No.2, the Peerage Law was enacted and precisely defined the inheritance and dignity of peerage and other procedures.
The title of duke was granted according to the following standard ('Joshaku' or conferring a peerage).
Subjects who rank under the Imperial Prince and Princess, and Shoo (Princes without imperial proclamation)
Though this bylaw existed, there were no examples of conferring the title of Duke due to a member of the Imperial family being demoted to a mere subject.
Kuge (court noble)
Former Sekke (line of regents and advisers)
These families were considered to rank the highest in court noble society and were qualified to be promoted to act as a regent to the emperor. There are five such families: Konoe, Kujo, Nijo, Ichijo, and Takatsukasa.
Buke (military authority)
It is the so-called former Shogun family and represents the family of Iesato TOKUGAWA. Only one such family exists.
Those who rendered a deed of valor
Those who rendered distinguished service to the state
They are classified broadly into three groups.
One group consists of those who were qualified to be given a peerage, but received a higher title than they should have been given, due to their great service being taken into account, although they did not make distinguished achievements. It includes four families of Sanjo (due to the achievement of Sanetomi SANJO), Iwakura (due to the achievement of Tomomi IWAKURA), Shimazu (of the former Kagoshima Domain) and Mori (of the former Choshu Domain), and in addition three more families of Saionji which were later promoted from the rank of Marquis (due to the achievement of Kinmochi SAIONJI), Tokudaiji (due to the achievement of Sanetsune TOKUDAIJI) and Mito-Tokugawa (due to the achievement of Atsuyoshi TOKUGAWA).
Another group consists of those who were granted the title of Duke after they were allowed to make a new family with their special achievement taken into account, although their head families already had the title. There are specifically two such families: that of Hisamitsu SHIMAZU, who was not the Lord of the Shimazu domain but had a great influence on the domain at the end of Edo Period as a guardian, and his descendants, and that of Yoshinobu TOKUGAWA, who transferred the headship of the family to an adopted child, Iesato TOKUGAWA, and lived in seclusion after Taisei Hokan (the transfer of power back to the Emperor), and his descendants.
The other group consists of those who were granted the title of Duke because of their great achievements although their families were not peers such as court nobles or Lords. They are the so-called new nobility. There are five such families: Hirobumi ITO, Iwao OYAMA, Aritomo YAMAGATA, Masayoshi MATSUKATA and Taro KATSURA, and if the Saionji family is included, six of nine Genro (elder statesmen) have received the title of Duke.
They received the title on July 7, 1884, if not otherwise specified.