The "kyu" in the name means "former" as it refers to the site where the temple once stood.
Down the mountain on the main road is the new Sentoji Temple, built, I believe after 1968 when a forest fire detroyed the last vestiges of the original temple.
Once the grandest of all the Rokugo Manzan temples in the central Kunisaki Peninsula area, some sources also suggest it was the first to be built.
A Torii tands on the path to the ruins, typical of the syncretic cult that existed here with Nio guardians at shrines, and torii at temples.
A pair of Nio stanf guard at what was the Goma Hall of the temple.
Sento-ji, as well as 27 other temples, are said to have been established in 718 by legendary monk Ninmon. This is of course legend, as records from this time are minimal, but Ninmon was a historal figure and his grave, and also the cave where he is said to have died, is a little higher up the mountain next to the Okunoin.
The temple was mostly detroyed, probably in 1560, when Otomo Sorin fought against and subdued the armed monks of Usa Hachimangu.
The Rokugo Manzan cult had strong connections with Usa Hachiman, being a Tendai-Hachiman cult primarily.
Obviously something continued to function here until the forest fire of 1968.
From the main temple site a path leads through the forest and up the mountain to the Okunoin.
Like most such places here, it is built into a cave. There are other caves with statuary and the cemetery that has Ninmons grave.
I was here at the start of day 4 of my second walk around Kyushu, this time following the Kyushu Fudo Myo Pilgrimage. For this first week I was roughly following the Kunisakihanto Minemichi Long Trail which closely follows the ancient yamabushi pilgrimage from Usa Hachimangu and then around the Rokugo manzan sites.