During the Edo Period, the cult of Mt. Fuji, which had been previously dominated by local religious institutions, becomes a major popular cult in the Kanto area. This process of popularization is accompanied by an increased attention to the chthonic world associated with the mountain, particularly the caves at the foot of Mt. Fuji. These places, both as sites of practice and as described in popular religious literature, acquire a central position and multiple functions in the popular understanding of the religious space of Mt. Fuji.
All of these views of the underground world at Mt. Fuji depict it as a place through which the human and the divine world can come into contact. The analysis of how this complex religious chthonic space is described and used at the popular level, allows us an insight in the way religion was used for the popular understanding of reality in the Edo period.