In ancient times, Empress Jingu visited Yorishima (Saburo-jima) on the way back to the capital after a punitive expedition to three Korean countries. Mitsuyama was named for this occasion.
Three granitic islands are said to be the shapes of Emperor Ojin, Emperor Chuai and Empress Jingu.
These islands are connected at the time of low tide.

Keiba-Junikake-Shinji
During the time of civil war, the shrine located on Saburo-jima moved to the current location, Oura, by the Lord Michitada Hosokawa. At that time, he included a holy horse in a procession as part of festival.
Later the event of the holy horse started and since then it has continued as a horse race.

This is a halophilous plant that only grows in a particular environment, such as a saltmarsh. Sea beans change in color into a deep red in the middle of October.
The reclaimed land around Yorishima is a unique place on Japan's main island where wild sea beans naturally grow.
In 1891, sea beans were discovered on an oyster island in Akkeshi-cho, Hokkaido. The Japanese name for the sea beans, Akkeshi-so, comes from the name of this town.
It is also called "Sangoso." (Chenopodiaceae, Salicornia)