, sometimes written as , was an ancient Japanese hereditary title denoting rank and political standing (a kabane) that, along with muraji, was reserved for the head of the most powerful clans during the Kofun period. The omi clans generally took their names from the geographic location from which they originated, such as the , the , the , the , the , and the , thus making them regional chieftains in their own right. All Ohomi above except Izumo (associates of Izumo Izumo-taisha) and Soga (Korea) are local to present day Nara Prefecture. By tradition, those who held the kabane of omi were considered , and they claimed (hundreds years later) that they were descendants of Emperor Kōgen (himself legendary), although there is no historical evidence to support this.The most powerful omi added the prefix to the omi title, and were referred to as . Examples of ōomi mentioned in the Nihon Shoki included during the reign of Emperor Richū, during the reign of Emperors Yūryaku and Seinei, during the reign of Emperor Keitai and the four generations of Sogas who dominated the title during the 6th and 7th centuries: Soga no Iname, Soga no Umako, Soga no Emishi and Soga no Iruka.This title denoted supremacy within the court, with titular power belonging to the Ōkimi (later denoted Emperor), whether or not he actually held power.These same characters () are pronounced Daijin to refer to titles beyond 670 A.D. in Daijō-daijin, Sadaijin, Udaijin, Naidaijin, etc.When the kabane system was reformed into the eight kabane system in 684 following a series of coup attempts, the powerful omi of the time were given the kabane of ason, which ranked second under the new system, and omi itself was dropped to sixth in rank.
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