A geyujo is a document that, when an officer in a position is replaced with another person under the Ritsuryo system (a system of centralized government based on the ritsuryo code) in ancient Japan, was issued confirming the change necessary for continuing office duties.
It was also called a geyu
During the Heian period and later, kageyushi conducted administrative audits based on geyujo.
No specification for geyujo was stipulated in the basic laws of Taiho Code and Yoro Code. However, shortly after that, the following system was introduced to supervise administration more thoroughly: When an officer was replaced with another person, the former officer made a document describing matters necessary for continuing office duties and handed it over to the new officer, and the new officer issued a certificate showing that he or she accepted the proper document. The certificate showing the acceptance of such a proper document was a geyujo. Only after submitting a geyujo to Shikibu-sho (the Ministry of Ceremonies), is the former officer able to assume the next official position. The new officer can not issue a geyujo when the predecessor had not yet completed his duty (for example, land tax had not been collected), and in such a case, a geyujo was issued only after the duty was completed (for example, the necessary land tax had been collected).
Although it was not clear when the geyujo system was introduced, a mikotonori (imperial edict) for promoting the geyujo system was issued on May 26, 733 (according to "Shoku Nihongi" - Chronicle of Japan continued). This mikotonori included the description of the following situations: Although instructed to follow the geyu system thoroughly in 731, a former kokushi (provincial governor) at a province returned to Kyoto before his successor arrived at the province, and the former officer could not be appointed to the new position because his successor did not issue a geyujo. Therefore, this mikotonori was issued to remind officers that they were responsible for issuing a geyujo and for submitting it to the Shikibu-sho. The geyu system described above was mostly concerned with kokushi, or more specifically, handing over a description of matters necessary for continuing office duties when a new kokushi was appointed.
Emperor Kanmu, who was an emperor from the end of the Nara period to the early Heian period, attempted to make kokushi perform his duties completely, and regulated in 782 that, if a government officer could not obtain a geyujo even after 120 days from when his successor arrived, the officer should be punished severely. Furthermore, the kageyushi position for checking geyujo was introduced in around 797.
After that, the kageyushi position was once abolished, but when it was introduced again (in 824), the geyujo system was changed considerably. Although formerly a geyujo was necessitated for kokushi alone, naikan (government officials in Kyoto) as well became necessary to have a geyujo issued when they left their positions, and became audited by kageyushi as well. Regulations also covered when it was impossible to accept a description of matters necessary for continuing the office duties, in such case, the successor should issue a fuyogeyujo (literally, not giving a geyujo) instead of a geyujo, and the kageyushi should judge the situation.
By the way, in the Heian period, the act of a predecessor accepting a geyujo was called "zuryo." Basically, a geyujo was issued at the site of the office concerned. Therefore, the kokushi who actually lived in his area of responsibility in order to control it directly, not one who lived in Kyoto and remotely controlled responsible area remotely, became called zuryo.
It is considered that geyujo functioned effectively during the first half of the Heian period. However, in the middle to the latter half of the Heian period, the trend of an office position monopolized by members of a specific family progressed, making geyujo for naikan gradually ineffective. Furthermore, in the first half of the Kamakura period, control by zuryo became existent in name only and geyujo for zuryo went out of existence as well.