"Kamiyama" means "God's Mountain" in Japanese.
The Kojiki is a collection of histories and legends of Japan's ancient past. One legend is called “The birth of the country” and in the legend, it says that “God gave birth to Japan". Awaji Island was the first to come out, and then Shikoku was next. Shikoku had four faces. Two were male, and two were female.
The male faces were Sanuki (present-day Kagawa) and Tosa (Kochi), and the female faces were Awa (Tokushima) and Iyo (Ehime). Each region had its own god which came down from heaven to govern the region, and Awa's god was a goddess called Ogetsu-hime no mikoto. This goddess is said to have descended from heaven onto Teppen-maru in Kamiyama's Jinryo area and governed Awa from there. At the base of the mountain is Kami Ichinomiya Oawa Jinja shrine, and that is where the goddess is enshrined. The name Jinryo means “god's domain”. This legend is the oldest legend in Kamiyama. In the middle ages, there were two villages located around the Akui River. Upriver was Kamiyama Village, and downriver was Shimoyama Village. Kamiyama (meaning “upper” mountain, not “god's” mountain) is still in use today, but Shimoyama faded from use. It's not clear where these original villages were located, but it seems that Kamiyama was from Jinryo to the headwaters, and Shimoyama was downstream.
More is known about the village locations in the early modern ages. It could be because as time progressed, people became more educated. Also, during the feudal period, the feudal government in Awa became more organized which resulted in better record-keeping.
In the present-day Kamiyama, there were the following villages. Kamiyama Village (this village was split into Kamibun (meaning upper portion) and Shimobun (meaning lower portion) during the feudal period), Sochi Village, Jinryo Village, Orono Village, Agawa Village, and Hirono Village. The villages continued to grow until the end of the feudal period. Even during the early Meiji Period, the old village system continued, but the Town and Village Districts Law changed the organization of the villages.
Kamiyama Village, Kamibun became Kamibun Kamiyama Village.
Kamiyama Village, Shimobun became Shimobun Kamiyama Village and merged with Souchi Village.
Souchi Village became Shimobun Kamiyama Village O-aza Souchi.
Agawa Village and Hirono Village became Ano Village, and within that village the old village names were left as O-aza Agawa and O-aza Hirono.
This structure continued until 1955, when Kamiyama-cho was created and Kamibun, Shimobun, Jinryo, Orono, and Ano all became part of Kamiyama.