The first example was FUJIWARA no Shoshi, who was originally named after the ridai, but Jotomonin, who was the mother of the two successive emperors, was cited as a good example; this became the ingo for a majority of all Nyoin.
初例は藤原彰子で、元々は里第に由来する命名だが、二代の国母となった上東門院は佳例であるとされたこともあり、女院全体の過半数を占める院号となった。