Ason was a hereditary noble title in Japan, used mainly between the Asuka and Heian periods. At first, it was the second highest, below Mahito, which was given to members of the Imperial family, but after the Heian period it became the highest of the eight noble titles: Ason, Mahito, Sukune, Imiki, Michinoshi, Omi, Muraji, and Inagi.