Ikishima Island is a small island in Sakoshi Bay with a circumference of 1.63 kilometers, an area of 8.1 hectares, and a peak elevation of 43.2 meters above sea level. It is said that Hata no Kawakatsu, one of Prince Shotoku’s favorite vassals, fled west by boat from Naniwatsu to escape persecution by Soga no Iruka and landed on Ikishima Island in the third year of Empress Kogyoku’s reign (644). It is also said that, following his death in Taika 3 (647), he was buried on the island, where his grave still remains. Since that time, the island has been a sacred property of Osake Shrine, and since long ago, ordinary people have been prohibited from setting foot on the island. The Ikishima Island Forest, the island’s well-preserved old-growth forest, was nationally designated as a Natural Monument in Taisho 13 (1924). The gentle waves in Sakoshi Bay are due to Ikishima Island’s presence there, and the island was responsible for Sakoshi’s prospering as a port shielded from the wind.