turned them into semi-permanent military bases. The American concept of the Ryukyu Islands was translated into Japanese as Ryūkyū Rettō (琉球列島), to which the Japanese government did not give a definition. The term Ryūkyū Shotō was avoided probably because the Amami Islands and the Daitō Islands lay outside the officially defined geographical extent of the Ryūkyū Shotō. The U.S. military assigned the name of Ryukyu to the entities it created. For example, the first university on Okinawa Island was named the University of the Ryukyus, which was given the Japanese name of Ryūkyū Daigaku (琉球大学). By contrast, entities created by Okinawans themselves tended to bear the name of Okinawa. The umbrella organization of the Okinawa reversion movement was named Okinawa-ken sokoku fukki kyōgikai (沖縄県祖国復帰協議会, literally, Okinawa Prefecture Council for Reversion to the Home Country). Thanks to the humiliating military occupation, Ryūkyū became loaded with negative connotations among Okinawans. Okinawa's northern neighbor, the Amami Islands, resisted much more strongly against the U.S. military's move to sever their centuries-old ties to mainland Japan and to annex them to what the Americans called the Ryukyus. At the early stage of military occupation, the U.S. military imposed the label Northern Ryukyu on the Amami Islands. While the people of Amami had no power to prevent the occupiers from using the English name, they expressed resistance by translating the much-hated term as Hokubu Nansei Shotō (literally, Northern Nansei Islands) in Japanese. A bitter memory of the U.S. military occupation strengthened the notion that the Amami Islanders were distinct from Okinawans. Even today, they occasionally voice opposition toward attempts to impose the label Ryūkyū on them. Ryukyu in natural sciences Some disciplines of natural sciences such as biology and geology have developed a distinctive notion of Ryukyu that does not align well with administrative or ethnolinguistic boundaries. After examining inconsistent and mutually conflicting uses of Ryukyu-related geographical names in the literature, Toyama (2014) proposed the following guidelines for natural sciences: Ryukyu Archipelago for the Nansei Islands, which covers the Senkaku and Daitō Islands, Ryukyu Islands for a narrower chain of islands between Kyushu and Taiwan, excluding the outlying Senkaku and Daitō Islands, and Three-way division of the Ryukyu Islands: the Northern Ryukyus, the Central Ryukyus, and the Southern Ryukyus. Watase's Line, the boundary between the Northern and Central Ryukyus, is drawn between Akusekijima and Kodakarajima of the Tokara Islands. Hachisuka's Line, or the Kerama Gap, marks