Ninmon (仁聞)
Ninmon (仁聞) was a legendary monk who is said to have founded 28 temples in various places in Kunisaki peninsula in Oita Prefecture in the Nara period. He was allso called Ninmon bosatsu (bodhisattva) and his name was also written as 人聞.
Summary
Many of the esoteric Buddhism temples in Kunisaki peninsula, which were called Rokugo-manzan (Mountain of Six Sanctuaries), have engi (writing about the history) which say these temples have been founded by Ninmon in 718. According to these engi, Ninmon first founded Sendo-ji Temple, then founded total 28 temples across the Kunisaki peninsula, and entered nirvana in Makura-no-Iwaya (cavern): the inner sanctuary of Sendo-ji temple, which was the first temple he founded. Also, many of the Magaibutsu (Buddha statues in cliffs and rocks) that still exist in Kunisaki peninsula, including Kumano Magaibutsu, are said to have been created by Ninmon. He is said to have made 69,000 Buddha statues. There is a theory that he founded Shusho-onie (fire festival).
These days, the theory that Ninmon was a fictional person is widely accepted. Temples of Rokugo-manzan had actually been the places for mountain worship, which existed in Kunisaki peninsula since ancient times. These temples came to have the forms of the temples of Tendai sect from the end of Nara period to Heian period. As a result of fusion of the temples and Hachiman shinko, believing the God of War (Hachiman-god) and centering on neighboring Usa-jingu Shrine, unique Mountain Buddhism culture with syncretism of Shinto and Buddhism is thought to have been formed. A theory says that people who founded the temples include monks such as Horen, Kegon, Taino and Kakuman, who practiced together as disciples of Ninmon and served as betto (administrator of a Buddhist temple) of Miroku-ji Temple: a Jingu-ji Temple of Usa-jingu Shrine.
As for Ninmon, it is thought that he was a Buddhist expression of Hachimanshin (God of War): an enshrined deity of Usa-jingu Shrine, or a god close to Hachimanshin.
Temples that are said to have been founded by Ninmon
Futago-ji Temple
Denjo-ji Temple (Maki Odo Hall)
Iwato-ji Temple (Kunisaki City)
Tennen-ji Temple
Sendo-ji Temple