The Spanish are believed to be the first people to discover Okinotorishima, but clear details such as the timing of the discovery are not known. Thereafter, in 1789 a British vessel discovered Okinotorishima, naming it Douglas Reef. (Ref. 1, 2)

In Japan, the island was introduced in Japan’s sailing directions issued by the government in 1892, and named as Parece Vela or Douglas Reef, indicating that since the Meiji period onwards the existence of Douglas Reef had been recognized by Japan. (Ref. 3) In 1922 and 1925 the Imperial Navy’s hydrographic survey ship Manshu measured the area, and Nautical Chart No. 2101, published in 1927, recorded the location of Douglas Reef. (Ref. 1, 4)

Although the location of Douglas Reef (Parece Vela Reef) is noted in the sailing directions of various countries, none of these records its attribution, and no assertions about sovereignty were made. (Ref. 1, 2)
 

Ref.1：Ministry of Foreign Affairs, “Regarding the affair of territorial sovereignty over ‘Douglas Reef’ (a coral reef),” Miscellaneous Matters Related to the Administration of Japanese Island Territories (Repository: Diplomatic Archives of the Ministry of Foreign Affairs of Japan, A-4-1-0-3)

Ref. 2：Kaji Ryota, “Okinotorishima wo meguru shomondai to nishitaiheiyo no kaiyo hozen hosho: Chugoku no kaiyo shinshutsu to kokuren kaiyo joyaku no kaishaku wo fumaete” [“Issues Surrounding Okinotorishima and Maritime Security in the Western Pacific: China’s Maritime Expansion and its Interpretation of UNCLOS”], Rippo to Chosa (Legislation and Research), Vol. 321, 2011, pp. 127-144.

Ref. 3：Hydrographic Department, Japan Hydrographic Journal, vol. 1 (1892), p. 281

Ref. 4：“Hydrographic Department Nautical Chart No. 2101: Tokyo Bay to Truk Islands” (1927)