There are thousands of small uninhabited islands and islets in Japan, many of them sacred and with small shrines on them. One hears often of sacred mountains, the places where the gods descend to, but sacred islands get mentioned much less.
There are many myths and stories of the gods coming from under the sea and from across the sea, the Japanese themselves arrived here by water, so its perhaps not surprising. The most famous sacred island is probably Miyajima, home to the Itsukushima Shrine, and it was for a long time kept uninhabited as an abode of the gods.
On my recent walk along the Japan Sea coast of Yamaguchi I encountered some of these sacred islands. Nowadays many of them are said to enshrine Benten, or Benzaiten, a syncretic deity associated with the sea. Small islands in lakes will often enshrine her. She was also conflated with the Itsukushima goddess.
The first photo is the tiny Megashima, which means Doe island. You can make out the torii on the right under the biggest tree. The next two photos are the larger Ogashima, 200 meters away, which means Stag island. Being a male/female pair they are considered Meoto (married) islands. As you can see in the third photo the shrine has buildings. No-one I asked could tell me which kami were enshrined there or if there was a story....
Further along the coast, the fourth photo is Noshima. You can just make out the torii on the beach to the left and a small honden behind it. Again no-one could tell me which kami is enshrined there. Further along in Susa Bay is Nakashima. A gentleman walking his dog told me Benten is enshrined there. As you can see it has buildings.