Kusuko Incident

The Kusuko Incident (薬子の変, Kusuko no Hen^?), also known as the Retired Emperor Heizei Incident (平城太上天皇の変, Heizei-Daijō-tennō no Hen^?), occurred in the early Heian period. In 810, Emperor Saga and ex-Emperor Heizei stood in opposition, but Saga's side quickly raised enough troops to resolve the confrontation, making Heizei become a monk. Heizei's lover the Naishi-no-kami (内侍^?) Fujiwara no Kusuko and her older brother the sangi Fujiwara no Nakanari were punished for the incident.

The incident was originally viewed as having been precipitated by Kusuko herself, and thus was called the "Kusuko Incident". In recent years, the view that the incident was caused by the division of power between the emperor of Japan and retired emperor under the Ritsuryō system has taken root. Since 2003, some Japanese high school textbooks have begun to refer to the incident as the "Retired Emperor Heizei Incident".

When Emperor Kanmu died in 806, his son Crown Prince Ate took the throne as Emperor Heizei. Heizei in turn appointed his younger brother Prince Kamino as crown prince. This decision is thought to have been influenced by Kanmu's opinion, and the fact that Heizei was sickly and his children were still young. Even so, an internal succession dispute in the court could not be avoided. The new emperor's younger brother by another mother, Prince Iyo, was accused the next year of plotting a coup, and ultimately committed suicide.

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