Emperor Kōken, also known as Empress Kōken, was the 48th ruler of Japan, reigning from 749 to 758 and again from 764 to 770. She was the daughter of Emperor Shōmu and became the first woman to ascend the throne twice. Her reign is noted for its cultural developments and the promotion of Buddhism. During her second reign, Kōken adopted the name Empress Shōtoku and focused on consolidating power and supporting the Tendai sect of Buddhism. She eventually abdicated in favor of her nephew, Emperor Junnin, but continued to exert influence behind the scenes until her death in 770.