Shibichudai was a household agency of the Empress Komyo (at the time when Shibichudai was established, she was already Empress Dowager Komyo since her husband the Emperor Shomu had abdicated the throne to his daughter the Empress Koken) which was established by FUJIWARA no Nakamaro (also referred as EMI no Oshikatsu) in 749.
紫微中台（しびちゅうだい）は藤原仲麻呂（恵美押勝）が749年に創設した、光明皇后（紫微中台創設当時、既に夫の聖武天皇は娘の孝謙天皇に譲位していたため、光明皇太后である）の家政機関。