Until the Meiji period (1868–1912), the were places of worship composed of a Buddhist temple and a Shintō shrine, both dedicated to a local kami. These complexes were born when a temple was erected next to a shrine to help its kami with its karmic problems. At the time, kami were thought to be also subjected to karma, and therefore in need of a salvation only Buddhism could provide. Having first appeared during the Nara period (710–794), jingū-ji remained common for over a millennium until, with few exceptions, they were destroyed in compliance with the Kami and Buddhas Separation Act of 1868. Seiganto-ji is a Tendai temple part of the Kumano Sanzan Shinto shrine complex, and as such can be considered one of the few shrine-temples still extant.
History
Founding
When Buddhism arrived in Japan, it encountered some resistance from pre-existing religious institutions and beliefs. One of the first efforts to reconcile pre-existing Japanese religion with Chinese Buddhism (in what would later be called shinbutsu shūgō, or amalgamation of kami and buddhas) was made in the 8th century during the Nara period with the founding of so-called jungūji or shrine-temples, religious complexes consisting of a shrine and a temple.
The first shrine-temple ever was very probably Usa Hachiman-gū, where a temple called Miroku-ji was completed in 779, however the earliest clearly documented case is that of a man who in 749 in Kashima, Ibaraki prefecture built a temple next to a shrine. Behind the inclusion within a shrine of Buddhist religious objects was the idea that the kami were lost beings in need of liberation through the power of Buddhism. Kami were then thought to be subject to karma and reincarnation like human beings, and early Buddhist stories tell how that the task of helping suffering kami was assumed by wandering monks. During his wanderings, some local kami would appear in a dream to a monk, telling him about his problems. To improve the kami's karma through rites and the reading of sūtras, the monk would build a temple next to the kami's existing shrine. The building of temples at shrines produced shrine-temple complexes, which accelerated the process of amalgamation of the two religions. As a result of the creation of shrine-temples, many shrines that had until then been just an open-air site, in keeping with tradition, became Buddhist-style groupings of buildings. In this fashion, Buddhism took over many sites that had until then been dedicated to local kami beliefs.
Kūkai himself left writings that make it clear he saw no problem in a mixed institution like the jingū-ji. There, Buddhist clergy would routinely recite sūtras on behalf of a kami, to guide him or her to satori. The institution had the government's approval and was meant on one side to be a tool to spread Buddhism to the provinces, on the other as a way to install religious representatives of the government there. During the Heian period a great number of temples were built next to shrines, but the term jingū-ji itself tended to disappear, suggesting that temples were taking over control of the shrines. How pervasive was Buddhism can be inferred from the fact that even Ise Shrine, a place considered even today the holiest of Shinto shrines, in 1868 included almost 300 Buddhist temples and practiced Buddhism. This in spite of strict rules which forbade Buddhism within the shrine itself.
Because none of the very few extant jingū-ji is intact, their composition is known only through old drawings and paintings. We know that the temple part of the shrine-temple complex consisted of several buildings, among them a main hall (), a pagoda, a Buddhist gate (mon) and a . The main priest was tellingly called or "shrine Buddhist monk", and was both a shrine priest and a Buddhist monk.
Two examples, which are however just recent reconstructions, are in Kyoto and in Nara.