Kōken

Empress Kōken was the 46th and 48th monarch of Japan according to the traditional order of succession. Seeking to protect the bloodline of Prince Kusakabe, her father, Emperor Shōmu, proclaimed her the first crown princess in Japanese history in 738, and she succeeded her father as empress regnant in 749 after he retired to become a Buddhist monk. With the backing of her mother, Empress Kōmyō, and cousin Fujiwara no Nakamaro, she was able to outmaneuver a largely hostile Daijō-kan. Her father died in 756, having named a cousin unrelated to the Fujiwara clan as Kōken's heir; this outraged her maternal Fujiwara relatives and their supporters, and Kōken replaced him with Prince Ōi, a close ally of her mother and Nakamaro. In 757, she headed off a conspiracy to overthrow her by Tachibana no Naramaro, and resigned the following year to serve as empress emerita, while Ōi reigned as Emperor Junnin.