Dejima is the name of an artificial island off the coast of Japan. In the Ghost in the Shell universe, it is the site of Japan's largest refugee camp. During the events of Ghost in the Shell: S.A.C. 2nd GIG the refugees attempt to secede from Japan and form an independent nation, creating a potential political issue involving hostilities and tensions. It is arguably the hideout of terrorist and fugitive Hideo Kuze.
The name and geography was appropriated from a real small fan-shaped artificial island built in the bay of Nagasaki in 1634 to constrain foreign traders such as the Portuguese, the Dutch and the Chinese.