Zasu (temples head priest) (座主)
A term of Buddhism, a different name of a chief priest. Generally speaking, it refers to the title of representative priests of the Tendai Sect.
A term of the history of the law system, an examiner in Kakyo (Chinese higher civil service examinations)
Zasu (a Buddhist term)
While this term originally referred to priests or chief priests who had the ability to unite many priests, later it came to mean the top priests in the Enryaku-ji Temple, which required the approval from the Imperial court in order to control all of the Tendai Sect. It seems that mainly the Imperial family assumed the position after the Kamakura period. After Haibutsu-kishaku (a movement to abolish Buddhism) in the Meiji period, approval from the Imperial Court was no longer necessary and the term was used as the title of the chief priest in Tendai Sect temples.
Zasu (a term of the history of law system)
Zasu refers to an examiner in Kakyo, Chinese higher civil service examinations. After the examinations, a successful applicant visited the examiners to show his gratitude for allowing him to pass the examinations and they made a contract as teacher and student. At that time, the examiner was called 'zasu,' meaning the master of that place.
Such relationships did not seem problematic from the viewpoint of a relationship between a successful Kakyo applicant and the examiner in charge, however, they produced bureaucratic alliances, which created a breeding ground for the development of factions. So, the denshi (palace examination as the final step of scholarly career in China) system was created in the Baisong period in order to abolish these negative effects. The theory was that if the ultimate examiner was the Emperor, zasu being the Emperor, the Emperor and each Kakyo bureaucrat already had the teacher-student relationship, irrelevant of bureaucratic parties.