Aptly called Kawai Jinja, the "Shrine of the Meeting of the Rivers," as it stands near the confluence of the Kamo and Takano rivers, it is dedicated (as the shrine informs us) to Tamayori-hime, the mother of Japan's first mythic emperor, Jimmu. She is revered for her naijo no ko, the fact that she helped her son with his great endeavor of establishing the dynasty (naijo no ko, helping husband or son along, was the highest women could aspire to in the old Japan and you still hear that phrase surprisingly often).
[Kawai Shrine, Shimogamo, Kyoto]
The shrine itself advertises that it was founded not long after Jimmu's time, but as this mythical hero ascended the throne in 660 BCE, that is historically quite impossible. Originally, it must have been a nature shrine, I guess, honoring the deities of the rivers who come together at this spot.
The link with Japanese mythology is probably a rather modern one, I suppose Edo-period or even Meiji, as Japan's imperial founding myths were neglected during most of the country's history and only became known again thanks to the efforts of Nativist historians in Edo times. To make things even more confusing, the deity honored in the main Shimogamo Shrine is also called Tamayori-hime, but hers is a different story, totally unrelated to the imperial founding myth.
The Kawai Shrine did exist in the 9th c., when it is mentioned in documents. In the past the shrine was rebuilt every 21 years, just like the Shimogamo Shrine itself, but that custom was abandoned in the 17th c. - the present buildings date from 1679.
What made the Kawai Shrine interesting to me, was the surprising connection with one of my favorite authors, Kamo no Chomei, the waka poet and courtier who became a recluse and wrote the Hojoki ("An Account of My Ten-Foot-Square Hut").
Kamo no Chomei (1155-1216) came from a family of priests attached to the Shimogamo Shrine and was himself called to priestly functions when still a young boy. He was intelligent and liked to study; at age 21 he shone at a poetry competition in the palace.
However, he did not obtain a major priestly position at the Kawai Shrine, nor was he very successful at court. These external factors combined with his personal inclination probably made him opt for the life of a recluse. In 2004 he took Buddhist orders and first lived for several years in the Ohara area northeast of Kyoto, before moving to the hills of Hino to the southeast of the capital where he built a flimsy cottage.
[Replica of Kamo no Chomei's hut, Shimogamo, Kyoto]
It was here, in the last years of his life, that he wrote the Hojoki. He laments the disasters that have ravaged Kyoto during his lifetime, both natural and man-made and reflects on the transitoriness of human life. Chomei finds peace in the beauty of nature, far from the vain striving of human beings.
Famous are the opening lines of the Hojoki: "The current of the river does not cease, and yet the water passing is not the same water as before. The bubbles that float upon its pools, now vanishing, now forming, never endure long: so, too, it is with human beings and their dwelling places here on earth."
Today, standing here at the Shrine of the Meeting of the Rivers it is clear where Chomei's inspiration came from!
Japanese text of Hojoki
English translation of Hojoki