No endorsement for the King of Japan envoy nor the Ojo-daijin envoy existed until Gafusei was introduced, and from the 1450s, pseudo envoys representing the Ojo-daijin envoy appeared with the intention of acquiring the rights and interests of trading, and in the 1470s, diplomatic boom by pseudo envoys called 'sending of diplomatic missions to Korea boom' occurred.
牙符制が導入されるまで日本国王使・王城大臣使に対する査証の手段は存在せず、1450年代から貿易利権を目当てに王城大臣使を名乗る偽使が出現し、1470年代には偽使により「朝鮮遣使ブーム」と呼ばれる偽王城大臣使の大量通交が発生する。