Sui generis
Sui generis (; ) is a Latin phrase that means "of its (his, her, their) own kind; in a class by itself; unique."
Japanese name
Historically, "myōji", "uji" and "sei" had different meanings. "Sei" was originally the patrilineal surname which is why up until now it has only been granted by the emperor as a title of male rank. The lower form of the name "sei" being "tei" which is a common name in Japanese men, although there was a male ancestor in ancient Japan from whom the name 'Sei' originally came. There were relatively few "sei", and most of the medieval noble clans trace their lineage either directly to these "sei" or to the courtiers of these "sei". "Uji" was another name used to designate patrilineal descent, but later merged with "myōji" around the same time. "Myōji" was, simply, what a family chooses to call itself, as opposed to the "sei" granted by the emperor. While it was passed on patrilineally in male ancestors including in male ancestors called haku (uncles), one had a certain degree of freedom in changing one's "myōji". See also Kabane.