Shika-no-shima island is located in Higashi-ku, Fukuoka-shi, Fukuoka Prefecture. It is a tombola island in the northern part of Hakata bay, and features two small islands connected by a bar of land. The island is approximately 11km in circumeference, with some 790 households and a population of about 3000. A tombola-form island such as this is very rare in Japan.

In 1784, two farmers harvesting rice on the island came across the golden seal of the Kan-no-wanona-no-Kokuo. It is thought that the seal was the same one referred to in the Chinese book 'Gokanjo' (the 'Book of the Later Han'), which was said to have been handed to the messenger of Nakoku from Kobutei (Emperor Guangwu).

Not only is the 'Gokanjo' a very important historical artifact, it is also a valuable national treasure. This golden seal reveals the early history of Japan, and is currently preserved and exhibited at the Fukuoka Museum. However, it is still unknown why the golden seal was buried on Shika-no-shima. One thing, however, is understood: that Shika-no-shima was the starting point from mainland Japan for overseas trade by the early rulers of the country. It is an ancient place and site of many historic incidents.