Ōmijima is a small island in the Sea of Japan just off the city of Nagato. The north coast of the island is eroded by the fierce waves of the Sea of Japan, resulting in unique rock formations that are visited by sightseeing boats from Senzaki Port on the mainland. Lake Ōmiko in the southwest of the island is a lagoon surrounded by sandbanks.

Tori village, one of the two main settlements, was a base for coastal whaling from the Edo period to the end of the Meiji period, using an ancient whaling practice where whales were driven into the shallow bay to be killed with harpoons. At Kōgan-ji Temple is a tall granite memorial erected in 1692 to the spirits of the foetuses of unborn whales whose mothers were slaughtered. You can learn more about historic coastal whaling at the Whale Museum near Kōgan-ji and at the Hayakawa Family Residence, the former home of the head of the whalers.