一いちの御み子こいちのみこMeanings1nounfirst-born imperial princearchaicArchaic term used in historical contexts for the eldest son of an emperor.一いちの御み子こは、古ふるい記き録ろくでは天皇てんのうの長ちょう男なんを指さす。In old records, 一の御子 refers to the emperor's eldest son.