This uninhabited island is located roughly 200 meters off the Ishinami Coast in southern Miyazaki Prefecture. The small island of roughly 3.5 kilometers in circumference, covering an area of 32 hectares, can be reached in just five minutes by boat. The island is currently home to about 90 Japanese macaques, and has been designated as the Kojima Monkey Habitat, a national natural monument. Around 1953, one of those monkeys began the practice of washing potatoes in seawater before eating them, and this behavior was subsequently passed on to its companions and offspring, making the monkeys famous throughout the world today as monkeys with culture. Accordingly, Kojima is also known as the birthplace of Japanese primatology, and is visited regularly by numerous researchers.

The following rules must be adhered to when members of the general public are observing the monkeys.
・No food may be brought to the island.
・You may not touch the monkeys.
・You may not take anything back from the island.
・You must never stare into the eyes of the monkeys.