According to "Sezoku senshin hi sho" (a ceremonial rule book written by the Emperor Gotoba), originally in the event of Chokin no Gyoko (New Year's visit to the Imperial Palace), the Emperor performed sayusa (left-right-left) and his retainers performed usayu (right-left-right), later, though, the custom changed so that the Emperor performed usayu, and the retainers performed sayusa.
『世俗浅深秘抄』によれば、朝覲行幸のとき天皇は左右左、臣下は右左右であったのが、のちに変じて、天皇は右左右、臣下は左右左となったという。