What does ASON stand for? 

Ason

Ason (朝臣), or Asomi in earlier form, was a prestigious title of ancient Japan, used mainly from the late 7th century until the 9th century, or from the Asuka period until the early Heian period. The title was created as a part of the eight-kabane system, proclaimed in 684, as its second highest rank. As such, asomi was initially given to the highest ranked noble clans whose genealogical origins were often claimed back to imperial princes. According to Nihon Shoki, the first creation of ason was in the 11th Month of the 13th year of the Temmu Emperor (684), then 52 clans were promoted to asomi rank. During the Asuka and Nara periods, new ason were created from court officers who made eminent achievements in their careers. Although the clans closest to the Imperial House, that is, descendants of Emperor Keitai, were intended to be promoted to Mahito, the first rank in the original eight kabane system, this fell out of favor with the nobility. In 802 Prince Yasuyo, a son of Emperor Kammu was designated Yoshimine no Ason Yasuyo, an indication that he had renounced his imperial status and became a member of the peerage. After that, the Mahito and other kabane designations became unpopular. During the Heian period, Ason turned into a universal style for courtiers without making any distinction of their ranks from other kabane.

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