Ushima was the base of operation of the Murakami Pirates and the cache site along the Shinonami Kaido cycling route offers a view of the island and the whirlpools of the Seto Nakai. The cache is a micro so bring a pen.
For information in Japanese- https://ja.wikipedia.org/wiki/能島
キャッシュはマイクロですのでペンを持参してください