Rokoku Hakase (Master of Clock) (漏刻博士)
Rokoku Hakase was a post appointed by Onmyoryo (a government office that had jurisdiction over calendar preparation, astronomy, divination, etc.) under the Ritsuryo system (a system of centralized government based on the ritsuryo code) in Japan.
The Japanese reading of the Chinese characters is 'tokitsukasa.'
The Tang name is Shishin 契壷司. Two officials were appointed to the post, and sometimes one or both were Kenkan (powerful officials). The post was equivalent to Jushichiinoge (Junior Seventh Rank, Lower Grade), but there were examples of Jugoi (Junior Fifth Rank) or Jurokui (Junior Sixth Rank) being appointed (according to "Shokugensho" (a history of court officials)).
In charge of 20 Shushincho (workers) selected from among forced laborers, the Rokoku Hakase supervised the rokoku (water clock) and at the same time measured the time, and at regular intervals ordered Shushincho to strike a bell installed in the Onmyoryo. During an imperial visit, one Rokoku Hakase and 12 Shushincho were obliged to join the procession, along with the rokoku.
However, it is considered that at a relatively early stage the essential skills of the rokoku were no longer needed, and during the Insei period (the period of government by the retired Emperor), the post became a government post held by members of the Kamo and Abe clans, or followers recommended by them. It is generally believed that 菅野季親 and 菅野季長were appointed as Rokoku Hakase as a master of nenzei (yearly predications), not rokoku. Rokoku was also installed in the provinces of Dazaifu and Mutsu (later Dewa Province was added), but Hakase was not appointed and Shushincho seemed to have operated the rokoku.