Who dated Kojijū?

Kojijū (小侍従; 1121–1202 CE) (also Matsuyoi no Kojijū) was a waka poet and Japanese noblewoman active in the late Heian period.

Her father was Ki no Mitsukiyo, and her mother was the poet Hanazono Sadaijinke no Kodaishin.

As a lady-in-waiting, she served the twice-empress Fujiwara no Tashi (who was wife, successively, to Emperor Konoe and Emperor Nijō), as well as in the court of the retired Emperor Takakura. Additionally, she took part in poetry contests organized by Emperor Go-Toba. During this time, courtiers were expected to be skilled poets, and a great deal of court life involved composing and exchanging poetry, as well as participating in poetry contests. Kojijū is designated a member of the Female Thirty-Six Immortals of Poetry (女房三十六歌仙, Nyōbō Sanjūrokkasen). She left a private collection of poems titled the Kojijū-shū.

Contemporaries noted her for her especial skill in composing poems that exactly suited the situation, particularly when writing a verse as a response to someone else's verse.

In 1179, she became a Buddhist nun.

Emperor Go-Shirakawa (後白河天皇, Go-Shirakawa-tennō; October 18, 1127 – April 26, 1192) was the 77th emperor of Japan, according to the traditional order of succession. His de jure reign spanned the years from 1155 through 1158, though arguably he effectively maintained imperial power for almost thirty-seven years through the insei system – scholars differ as to whether his rule can be truly considered part of the insei system, given that the Hōgen Rebellion undermined the imperial position. However, it is broadly acknowledged that by politically outmaneuvering his opponents, he attained greater influence and power than the diminished authority of the emperor's position during this period would otherwise allow.

Posthumously, this 12th-century sovereign was named after the 11th-century Emperor Shirakawa. Go- (後), translates literally as "later"; and thus, he is sometimes called the "Later Emperor Shirakawa", or in some older sources, may be identified as "Shirakawa, the second" or as "Shirakawa II".

Unusually, the years of Go-Shirakawa's reign are more specifically identified by more than one era name or nengō; Kyūju (1154–1156) and Hōgen (1156–1159).

He was de facto the last true emperor, before the shogun became the actual head of the country after Go-Shirakawa's death in 1192 until the Meiji Restoration in 1868.