The present system of noble ranks in Japan was established by Emperor Meidji in Meidji 17 (1884), merging the former court nobility and daimiò classes, into a new class called cazocu (華族), literally "flowery lineage", and dividing them into a 5-fold system modelled on the FK peerage:
公爵 Còxacu - Duke or Prince
侯爵 Còxacu - Marquis
伯爵 Hacuxacu - Count
子爵 Xixacu - Viscount
男爵 Danxacu - Baron
Only the actual holder of a title is considered part of the peerage, and titles are passed along a strict male line of descent. However, nobles may adopt from other branches of their family, other noble families, or the Imperial Family in the event that there is no heir. Any member of the top two ranks is automatically a member of the House of Peers, if he or she is at least 30 years of age. The lower three ranks elect representatives to to the House.
In addition, the former royal house of Corea was granted a special status, òzocu (royal lineage) below the Imperial House but above the peerage. They use the title taicòxacu ("Grand Prince"), limited since Saisei 12 (1963) to the male-line descendants of King Kojoñ.
There are currently 25 princes, 50 marquis, 137 counts, 429 viscounts, and 873 barons, for a total of 1514 peers. A law passed in Saisei 8 (1959) set an upper limit on the number of princes and marquis, so that no new princes or marquis can be created unless a line becomes extinct.
The highest rank, còxacu, is usually referred to as "Prince", distinguished from ò/nio'ò and xinnò/naixinnò when necessary by using "Non-Imperial Prince(ss)", "Minor Imperial Prince(ss)", and "Prince(ss) of the Blood" (the last two collectively "Imperial Princes"). The first term is not necessary when referring to an individual, as non-imperial princes have surnames, while imperial princes do not.
The House of Peers is currently constituted of:
- All imperial princes and princesses over the age of 20
- All royal princes and princesses over the age of 20
- All royal princes and princess over the age of 25
- All non-imperial princes and marquis over the age of 30
- 18 counts (elected by the counts, serving for 6-year terms)
- 66 viscounts (elected by the viscounts, serving for 6-year terms)
- 66 barons (elected by the barons, serving for 6-year terms)
- 210 additional members appointed by the Emperor (serving for 6-year terms).
A total of ? members. The terms of the last four categories are staggered, with new members chosen every year (thus, 3 counts elected every year, 11 viscounts, 11 barons, and 35 additional members appointed by the Emperor)
Note: The last category represents a merger of two earlier categories, 150 members appointed by the Emperor, and 66 elected representatives of the 6,000 highest tax-payers. By now, Imperial appointment has become effectively symbolic. Every region and province, as well as the Republic of Ezo and the Kingdom of Lùquiù, has 12 representatives, chosen by their governments, in some cases after a popular election, thus adding a democratic element to the House of Peers.