It was customary during the Edo period that, when a new year commenced, the shogun sent Koke (position in the Tokugawa shogunate which mainly handled ceremonial matters) as his representative to present the emperor and retired emperor (In) a New Year's greeting and, in return, the emperor and the retired emperor sent an envoy to give an imperial reply (the emperor's envoy was called chokushi and the retired emperor's envoy was call inshi or sentoshi (because, at that time, the retired emperor administered the government by cloistered emperor) to Edo (present Tokyo) in March.
新年が来ると幕府将軍は高家を名代として天皇と上皇(院)に対して新年祝賀の奏上をおこない、天皇と上皇はそれに対する勅答の使者（天皇の使者は勅使といい、上皇の使者は院使または仙洞使(当時上皇は仙洞御所という所で院政を執ったため)という）を3月に江戸へ下向させるのが江戸時代の毎年の慣例であった。