Kōnin Accedes and Yamabe Replaces Osabe as Heir

Prince Shirakabe became Emperor Kōnin after Empress Shōtoku's death in 770. A grandson of Emperor Tenji, he returned the succession to Tenji's descendants after the long predominance of Tenmu's line. His wife Inoe, a daughter of Emperor Shōmu, became empress, and their son Prince Osabe was designated crown prince.

In 772, Inoe was accused of cursing Kōnin. She lost her title, and Osabe was removed as heir. They were subsequently confined in Yamato. Another of Kōnin's sons, Prince Yamabe, was designated crown prince in 773, with support from influential ministers including Fujiwara no Momokawa.

Inoe and Osabe died on the same day in confinement in 775. The accusations and their removal are recorded events; they do not establish that either committed the alleged offense. Their deaths left the displaced branch without its original claimants. Yamabe eventually succeeded Kōnin as Emperor Kanmu in 781. His path to the throne had depended on this change in the designated succession, rather than on an unbroken expectation that he would inherit from 770.