Nemuro Subprefecture
Ketoy had no permanent habitation prior to European contact, but was visited in summer by the Ainu tribes from Rasshua for hunting. Members of the Russian expedition who visited the island in 1811, found the remains of a wooden cross with the word "God", which was presented as evidence of the gradual Christianization and Russification of the Ainu; however, a census in 1831 found no permanent inhabitants. Claimed by the Empire of Russia, sovereignty was passed to the Empire of Japan per the Treaty of Saint Petersburg along with the rest of the Kuril islands. The island was formerly administered as part of Shimushiro District of Nemuro Subprefecture of Hokkaidō. After World War II, the island came under the control of the Soviet Union, and is now administered as part of the Sakhalin Oblast of the Russian Federation.