This refers to Fujiwara no Noriko (Senshi) 藤原詮子 (962-1001), who had been a consort of Emperor En’yû 円融 (959-991; r. 969-984). After his death, she took orders and was henceforth referred to with the title she is in the original text, nyôin 女院 , so it seems likely that this poem can be dated between 991 and 1001.