Fujiwara no Kaishi (藤原懐子)
FUJIWARA no Kaishi (or Chikako) (945 - May 16, 975) was the first daughter of Regent FUJIWARA no Koretada from the Northern House of the Fujiwara Clan in the mid-Heian period. Her mother was Princess Keishi, a daughter of Emperor Daigo's son, Imperial Prince Yoshiakira. She was a nyogo (consort) of Emperor Reizei, and Emperor Kazan's mother.
Around 963, she entered the Imperial Court to serve Imperial Prince Norihira (who later became Emperor Reizei). In 967, she became a Koi (court lady) when Emperor Reizei ascended the throne, and later the same year, she was made a nyogo and granted Jushiinoge (Junior Fourth Rank, Lower Grade). In 968, she gave birth to her first child, Prince Morosada (Emperor Kazan), who became an imperial prince after the abdication of his father, Emperor Reizei in 969. In 972, her father, Koretada, died. In 974, she was awarded Junii (Junior Second Rank), and in 975, she died at the age of thirty-one. In 985, she was given the title of Empress Dowager when Emperor Kazan ascended the throne.
Although Emperor Reizei had married his Empress, Imperial Princess Shoshi, while he was Crown Prince, she was afraid of his insanity, stayed away from him, and therefore, had no child with him. Although Kaishi was a nyogo, she was the only consort with whom Emperor Reizei had children while he was on the throne, giving birth to one son and two daughters. Her son, Imperial Prince Morosada, became Crown Prince supported by his powerful maternal grandfather, Koretada. However, Koretada, who served as regent, died at the age of fifty without seeing his grandson ascend the throne, and Kaishi and her brothers died one after another. This meant that Emperor Kazan was left without any powerful guardians other than FUJIWARA no Yoshichika, his young uncle, and was forced to abdicate after a reign of only two years. Her second daughter, Imperial Princess Sonshi, who became a nyogo of Emperor Enyu, died shortly after becoming a nun and none of Kaishi's children led a prosperous life.