Nyogo: Originally a nyogo referred to another name for Hin (a mistress) but this term evolved into a position of one in pursuit of the rank of an empress and chugu; therefore, a lady who planed to become an empress or a chugu became a nyogo first, according to custom.
女御（にょうご）…本来は嬪の別称であったが、後に皇后・中宮に次ぐ地位とされてこれらの地位に昇る予定の女性でもまず女御になるのを慣例とした。