Okinawa is now considered as Japanese territory, without challenge from most world powers. However, this is debatable from a historical viewpoint. The Ryukyu Kingdom which dominated the islands was integrated into Japan in 1879. The transformation is seen by Wang Hui as a process of modernization. This chapter argues the issue from an international law perspective. It shows that Ryukyu was an independent State as demonstrated by the 1854 Ryukyu–US Treaty, although it sent regular tributes to China. The Japanese integration by coercion is not justifiable. The people of Ryukyu were willing to continue being a tributary State rather than part of Japan. Britain, as the greatest colonial power, did not object. China and the US attempted to intervene in this affair, but no treaty has so far been concluded. Therefore, the status of Ryukyu/Okinawa remains unresolved and may need to be revisited, while putting the history context into consideration.