Bokan is an organization which was in charge of the household management of the supreme leader of a temple (betto [administrator of a Buddhist temple] or sango [three monastic positions with management roles at a temple]) and so on, or the monks who belonged to such an organization in and after the Heian period. Bokan is similar to the Mandokoro (Administrative Board) in the everyday world.
Living quarters used by monks in a temple were called sobo. Especially the monks who were in charge of personal care and assisting the clerical work of betto or sango at the sobo, were called bokan. Later, mandokoro for court nobles and samurai families began to have similar positions such as betto (chief administrator) (betto here is a different position from that in Buddhist temples), koto (a secretary) or azukari (an additional post to the chief of Naizenshi). Especially when the young people in the Imperial family or court nobles began to join temples as monzeki (successor of a temple), important posts came to be succeeded by these monzeki. Then the monks who serve monzeki came to be called bokan. Monzeki took control of the personnel matters of sango and lower rank monks, and appointed bokan who would serve himself. In addition, monzeki exercised their right under Eisenji (decree allowing certain rights permanently) and granted sokan (official positions given to Buddhist priests by Imperial Court) such as hokkyo (the third highest rank for Buddhist priests), hogen (the second highest rank for Buddhist priests) or hoin (the highest rank in the order of priesthood) to such bokan to secure their loyalty. On the other hand, hereditary bokan families appeared who were familiar with the works conducted by bokan since the family successively served as bokan. Monzeki treated them also the same way as the bokan serving him, then had them under his influence. The Shimotsuma clan at the Hongan-ji Temple is a representative example. In the Edo period, more and more monzeki became court nobles. Therefore, only the monks who served monzeki and were in the highest rank came to be called bokan and other lower rank monks came to be categorized into shodaibu, hokumen or samurai; such categorization formed a hierarchy similar to that of court nobles.