Sokutai is the full official dress worn by emperors, aristocrats and courtiers since the Heian Period (794). It is also called Hino-shouzoku.
The word Sokutai, was originally found in the Analects of Confucius, where it meant layered clothes tied with an obi belt and it indicated a full set of dress.
Sokutai consist of a crown, hitoe clothes worn over underwear followed by akome and shitagasane clothes with a long sash called kyo hanging in the back.  Crimson under pants and baggy outer trousers are then added and finally, an outer robe called hou, which is tied with a leather belt containing stone decorations called sekitai.
Sokutai, based on the court uniforms worn by the government officials under the ritsuryo codes, became the full official dress of the Imperial Court. Those who were among military officers, civil officials in Nakatsukasasho who oversaw imperial affairs and aristocrats who held the sangi position or higher and who were granted Imperial permission were allowed to wear a sword. As time passed, sokutai has become more ceremonial, only being worn in special occasions.
There are two kind of the hou outer robe: houeki which the civil officials wore and ketteki which allowed more free movement and was worn by military officials.
Sokutai is traditional and elegant full official wear for the emperor as well as aristocratic and government officials.