The word 'Nyogo' first appeared in the article about Emperor Yuryaku in 'Nihonshoki,' but in fact, KI no Otona and Kudaranokonikishi kyoho who were made Nyogo during the reign of Emperor Kanmu were the beginning of Nyogo.
初見は「日本書紀」雄略天皇の条であるが、実際は桓武天皇のとき紀乙魚（きのおとな）・百済王教法などを女御としたのに始まる。