The Monshu (門主), or keeper of the gate is a term sometimes used in Japanese Buddhism to denote the head of a monastery, as in the case of Jōdo Shū and Tendai Buddhism, but in the case of the Nishi Honganji sub-sect of Jōdo Shinshū Buddhism, it refers to the spiritual leader of the sect, and direct descendant of its founder Shinran.
The Monshu in Jōdo Shinshū Buddhism being the guardian of Shinran's mausoleum, as well as the head of the sect started when the youngest daughter of Shinran, Kakushinni, installed her son to be the custodian of the small shrine which held Shinran's image and ashes at Ōtani (Kyoto).
In time the small shrine grew into what is now the Honganji temples (east and west) in Kyoto, Japan. When the temple split into two temples, the West Temple, or Nishi Honganji continued to use the term Monshu, while the East Temple, or Higashi Honganji gradually adopted the term "Hossu".
In the line of Monshu descendants, noteworthy Monshū include:
As of writing, the current and 24th Monshu of the Nishi Honganji temple is Sokunyo Shōnin (Ōtani Kōshin, born 1945). When he retires, he will be succeeded by his son, the Shinmon (新門), Sennyo Shinmon (Ōtani Kōjun, born 1977).