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Territorial Sovereignty over the Senkaku Islands*1
Toshio Okuhara
I. Introduction
The Senkaku Islands are part of the Nansei Shoto Islands of Japan and belong to Ishigaki City, Okinawa
Prefecture. They are located between longitude 123º30’ and 124º35’ E and latitude 25º45’ and 26º0’ N
and consist of eight islands. The largest of the islands is Uotsuri Island, with a land area of approximately 4.32 km2. It is followed by Kuba Island (1.08 km2), Minamikojima Island (0.463 km2), Kitakojima
Island (0.302 km2), and Taisho Island (0.154 km2). In addition, the islands include Okinokitaiwa,
Okinominamiiwa, and Tobise.
The total land area for the Senkaku Islands are no more than 6.32 km2, nearly equivalent to theareas of Lake Yamanaka in Shizuoka Prefecture or Taketomijima Island of the Yaeyama Gunto Islands. In
May 1969, the United Nations (UN) Economic Commission for Asia and the Far East (ECAFE) released
the results of a joint survey on mineral resources in the East China Sea continental shelf, identifying potential oil and natural gas resources especially in the continental shelf around the Senkaku Islands. Thisbrought attention to the existence of the islands, and from 1971, China and Taiwan began to officiallyclaim territorial title over the islands.
As will be discussed later, the Senkaku Islands were incorporated into Japanese territory during the
Meiji Period, in accordance with the legal principle of occupation of terra nullius in international law.
China and Taiwan nevertheless assert that the islands were their territories prior to the incorporation
into Japanese territory, and moreover, were appertained to Taiwan.
According to Japan’s position, the Senkaku Islands were never part of the territory of China andChina and Taiwan had consistently acknowledged prior to 1969 that the islands were the territory ofJapan. For example, in an article entitled “Battle of People in Ryukyu Islands against U.S. Occupation” inPeople’s Daily (China) dated January 8, 1953, those islands were included as “Houkatsu Senkaku Shoto”(Senkaku Group of Islands) within part of the Ryukyu Islands. Similarly, a map entitled “Map of Japan”
made by the editorial office of a cartographic publisher in Beijing in November 1958 treats the Senkaku
Islands as clearly part of Japanese territory.
Before 1969, Taiwan not only failed to treat the Senkaku Islands as part of the islands appertained
to Taiwan, but it clearly understood the islands as being included in the Ryukyu Islands and referred tothem by their Japanese names. For instance, Taiwansheng Difang Zizhi Zhiyao [The Outline of the Local
Self-Government in Taiwan Province] printed in November 1965 by the Taiwanese provincial government specifies the Pengjia Island (located closer to Taiwan than the Senkaku Islands by approximately
150 km) as the northern boundary of Taiwan province. Zhonghua Minguo Nianjian [The Yearbook of the* This article was originally published as 奥原敏雄「尖閣列島の領有権」『現代の法律問題―時の法を探る―』法学書院、1979 年、237-260 頁 .

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Republic of China] of October 1968 also regards the Pengjia Island as northern boundary and Mianhua
Island as eastern boundary of Taiwan.
In Volume 1 (East Asia Nations) of World Atlas, published in Taiwan in October 1965 by the National
Defense Research Academy and the China Geological Research Institute of Taiwan, the Senkaku Islands
are identified as Japanese term “Senkaku Gunto,” and the names of their individual islands are listed. The
Japanese name of Uotsuri Island is used for Diaoyutai, accompanied with the Japanese pronunciationin Roman letters. Kobi-sho Island and Sekibi-sho Island are listed with their respective Japanese names,
Kuba Island and Taisho Island, in parentheses. The names of these two islands are in Roman letters to
be able to read them by their Japanese pronunciation. Kitakojima Island and Minamikojima Island arelisted as well but not accompanied with Roman letters. However, both are names given by Japan. The
Senkaku Islands are marked as Senkaku Group of Islands together with its correct Japanese pronunciation, “Senkaku Gunto.” In addition, a 1970 geographical science textbook for public junior high schools
in the Republic of Taiwan treats the Senkaku Islands (“Senkaku Gunto” in the original map) as part of
the “Dai-Ryukyu Gunto” [Great Ryukyu Group of Islands] and Japanese terminology is adopted, such as
Uotsuri Island, Minamikojima Island, and Kitakojima Island.
Accordingly, Chinese and Taiwanese territorial claims over the Senkaku Islands not only contradict
the facts above but also go against the estoppel principle of international law.
Nevertheless, so far as China and Taiwan assert title of these islands, their reasoning needs to beunderstood and critically examined. At the same time, it is necessary to clearly demonstrate grounds forJapan’s sovereignty over the Senkaku Islands as a basis of our criticisms.

II. Territorial Incorporation of the Senkaku Islands
Intention of extending sovereignty
Japan began to show its intention of extending sovereignty over the Senkaku Islands through official
maps and other means in around 1879. In March 1879, Dai Nihon Zenzu [The Complete Map of Great
Japan] edited by Chubei Matsui was published under the Interior Ministry’s censorship. In its map of
the Ryukyu Islands, the location of the Senkaku Islands are almost accurately charted. Uotsuri Island isnamed “Wahe-san” and its nearby islands (Minamikojima, Kitakojima, and some reefs) are collectively
named “Nakadaka San.” Names of these islands are marked both in Japanese and Roman letters. Kuba
Island and Kumeaka Island are listed in Japanese term “Koubisho” and “Takaosho” respectively but without Roman letters.
Dai Nihon Zenzu is an important map as it was published shortly before the enforcement of theprefectural system in Okinawa (Ryukyu Domain became Okinawa Prefecture about one month after
the publication. Although the area was still called Ryukyu Domain, it was placed under the jurisdictionof the Interior Ministry from 1874. Thus, enforcement of the prefectural system to Ryukyu Domain
does not affect the legal status of the islands as a territory of Japan). Maps which were published after
the enforcement of the prefectural system include Dai Nihon Fuken Kankatsu Zu [Map of Prefectural
Jurisdiction of Great Japan] of December 1879. This map is an official one edited by the Geography
Bureau of the Interior Ministry. Dai Nihon Fuken Kankatsu Zu clearly indicates that the Senkaku Islands
are comprised in the Ryukyu Islands and it marks the names besides some islands (Sekibi-sho Island,
however, was not illustrated).
Subsequently, Japan repeatedly showed its intention of extending sovereignty over the Senkaku
Islands. In “Map of Okinawa Prefecture” in Dai Nihon Fuken Bunkatsu Zu [Map of Prefectural Divisionof Great Japan] published by the Geography Bureau of the Interior Ministry in 1881 (revised in 1883),

2the Senkaku Islands are depicted (except for Sekibi-sho Island) but the names of the islands are not listed.
From 1886, not only maps but also the coast pilots of Japan began to include the Senkaku Islands as part of
territory of Japan. Kanei Suiroshi [Coast Pilot Directory of Oceans], Volume 1, Part 2 published in March
1886 by the Japanese Navy Hydrographic Bureau mentions the Senkaku Islands in Section 10, “Shunan
Shoto Islands.” The directory uses “Senkaku Gunto” as a collective term that included Uotsuri Island andits nearby islands. For the first time, the name “Senkaku” was applied in reference to a group of islands(Taiwan Suiroshi [Coast Pilot Directory of Taiwan] of 1873 published in Japan identifies Minamikojima
Island as Senkaku. It is the literal translation of “Pinnacle Island,” the name given to Minamikojima
Island in the U.K. Navy’s coast pilot directory.). In addition, the Senkaku Islands are referred to in Section
3 “Nansei Shoto Islands” of Nihon Suiroshi [Coast Pilot Directory of Japan] Volume 2, published in July
1894 by the Japanese Navy Hydrographic Department (this is deemed to be the first document which applies the term “Nansei Shoto Islands” and includes the Senkaku Islands within the scope of the Islands).
In 1885, there was another important development. For the first time, the government ordered
Okinawa Prefecture to conduct a survey on the Senkaku Islands. In 1885, the Interior Minister (Aritomo
Yamagata) internally ordered Nagayoshi Morimoto, Grand Secretary of Okinawa Prefecture in Tokyo, to“investigate the uninhabited Kumeaka Island and two other islands dotted between Okinawa Prefecture
and Fuzhou of the Qing Dynasty.” First, the Governor of Okinawa Prefecture (Sutezo Nishimura) was
informed by Eiho Oshiro (local official of logging in Misato Magiri) through Hyogo Ishizawa (Fifth
grade officer of Okinawa Prefecture) that “before the abolishment of the feudal domain system, Eiho
Oshiro confirmed at a short distance the islands at the time of travelling to the Qing Dynasty for official and private purposes.” This investigation report entitled Kumeakajima Kubajima Uotsurijima no
Santo Torishirabesho [Report on the Investigation of the Three Islands of Kumeaka, Kuba, and Uotsuri]
was submitted to the central government by the Governor of Okinawa Prefecture as an attachment to a
proposal addressed to the Interior Minister on September 22, 1885, entitled Kumeakajima hoka Nitou
Torishirabe no gi nitsuki Jyoushin [Proposal for the Survey on Kumeaka Island and Two Other Islands].
Following this, the Governor of Okinawa Prefecture dispatched Hyogo Ishizawa and five other officials to the Senkaku Islands aboard “Izumomaru” of Osaka Shosen (Osaka Shipping Co.), in order toinvestigate and report the configuration of harbors as well as the prospect of land development and local
production. There are two such reports. One of them is Hyogo Ishizawa’s Uotsurijima hoka Nito Jyunshi
Torishirabe Gairyaku [Outline of the Investigation and Survey of Uotsuri Island and Two Other Islands].
The other is Uotsuri Kuba Kumeakajima Kaikou Houkokusho [Report on the Navigation of Uotsuri, Kuba,
and Kumeaka Islands] prepared by the captain of Izumomaru, Tsurumatsu Hayashi.
Territorial incorporation measures
The survey by Izumomaru is significant as it further affirmed Japan’s intention to hold title over the
Senkaku Islands through concrete exercise of state sovereignty. This survey is also important in that theGovernor of Okinawa Prefecture asked the Interior Minister’s advice on whether or not national markers
should be erected on the islands. At that time, the Governor of Okinawa Prefecture had a slight concern
about erecting markers since the Qing Empire was familiar with the islands. The Governor thus simply
inquired the Interior Minister as to whether or not markers should be erected.
However, after reviewing the survey report of Izumomaru, the Governor of Okinawa Prefecture
thought that there were no particular problems associated with placing the Senkaku Islands under thejurisdiction of Okinawa Prefecture. Therefore, in its second proposal to the Interior Minister (dated
November 5, 1885), Uotsurijima hoka Nito Jitti Torishirabe no Gi nitsuki Jyousin [Petition for Land Survey

3

in Uotsuri Island and Two Other Islands], the Governor actively requested more of the erection of jurisdiction markers.
Interior Minister Aritomo Yamagata, upon receiving the first proposal from the Governor of
Okinawa Prefecture, prepared a draft proposal for the Grand Council of State, but before submitting it,
sent a letter to Foreign Minister Kaoru Inoue to ask for his opinion. This letter (dated October 9, 1885)
was entitled, Okinawaken to Shinkoku tono Aida ni Sanzaisuru Mujintou no Gi nikanshi Iken Toiawaseno Ken [Memorandum requesting comments on uninhabited islands sparsely situated between Okinawa
Prefecture and the Qing Dynasty]. In the draft report for the Grand Council of State, which was enclosedwith the letter, the Interior Minister expressed the following view:
The aforementioned islands appear to be identical with the islands reported in the Records ofMessages from Chong-shan, but they were mentioned as a mere direction in the course of voyage
and showed no particular trace of having been under the control of the Qing Dynasty while theislands’ names were different between them and us. They belong to the uninhabited islands near
Miyako, Yaeyama and others under the control of Okinawa and, therefore, there should be no problem with the prefecture surveying them and erecting national markers on them.
It is important that the Interior Minister mentioned that the islands “showed no particular trace of
having been under the control of the Qing Dynasty” because he considered the islands “terra nullius”
which did not belong to any state.
Nonetheless, due to the Foreign Minister’s objection, the Interior Minister’s opinion that “there
should be no problem with the prefecture erecting national markers on them” did not lead to the erection of national markers at this time. This is, however, not because the Foreign Minister considered
Kumeaka Island and other islands as part of the territory of the Qing Dynasty. The views of the Interiorand Foreign Ministers did not differ on the legal status of the islands. This is also evident from the factthat the Foreign Minister approved the land survey by Izumomaru. It should furthermore be noted that
the Foreign Minister’s statement, “We should deal with [them] some other day,” illustrated that he was
not opposed to the erection of national markers and the development of the islands per se. He was no
more than raising an issue with their timing.
As for why the Foreign Minister considered that it was too early to erect national markers, he explained as follows in his response to the aforementioned letter from the Interior Minister addressed to theForeign Minister (October 21, 1885), entitled Okinawaken to Shinkoku tono Aida ni Sanzaisuru Mujintou
ni Kokuhyoukensetsu ha Enkisuru hou Shikarubeki mune Kaitou no ken [Reply suggesting the postponingof the erection of national markers on uninhabited islands sparsely situated between Okinawa Prefecture
and the Qing Dynasty]:
Concerning the aforementioned islands, they are in proximity to the national border with the
Qing Dynasty, their circumferences appear smaller than those of the Daito Islands after our on-site
survey and in particular, their names are being attached by the Qing Dynasty. There are rumors
recently circulated by Qing newspapers and others, including one that says our government is goingto occupy the islands in the vicinity of Taiwan that belong to the Qing Dynasty, which are arousing
their suspicions towards our country and frequently alerting the Qing government for caution. If
we took measures such as publicly erecting national markers, it would result in making the Qing
Dynasty suspicious.

4In short, the Foreign Minister judged that it was not diplomatically appropriate to take measures,such as publicly erecting national markers, on the islands of which both Japan and the Qing Dynasty
were fully aware of the existence and which were close to the national borders of both states, even if theislands did not belong to any state, at a time when Qing newspapers and others were raising alert to the
Qing Dynasty seemed to show some interests on the islands.
Certainly, given the small size of the islands, there was no necessity to take measures, such as hastily
erecting national markers, in the face of the risk of causing a diplomatic friction with the Qing Dynasty,
at least at that time. This was not only a time when confrontations between Japan and the Qing Dynasty
over the attribution of Ryukyu had lingering effects but also a time when many crucial diplomatic issues
were being dealt with between Japan and the Qing Dynasty. In addition, Foreign Minister Inoue’s cautious stance towards Qing diplomacy influenced his decision over this issue.
The Governor of Okinawa Prefecture filed his third and fourth proposals in 1890 and 1893. On
January 13, 1890, the Governor of Okinawa Prefecture (Kanji Maruoka) submitted a proposal to theInterior Minister at the request of the Yaeyama Islands Local Office to place the jurisdiction over theuninhabited Uotsuri Island and two other islands based on the necessity for fishery control. In responseto the proposal of the Governor of Okinawa Prefecture, on February 7, 1890, Kencho Suematsu, Directorof the Prefectural Affairs Bureau of the Interior Ministry, requested the Governor to submit copies ofthe documents regarding the details of the December 5, 1885 order. Although the Governor sent the
copies to him on February 26 and requested a response to his earlier proposals, the issue seemed to beleft untouched for a while.
The government finally approved the proposal of the Governor of Okinawa Prefecture filed on
November 2, 1893, which also gave fishery control as the reason for placing the islands under the jurisdiction of Okinawa Prefecture, similar to the 1890 proposal. It was not until April 14 of the following
year, 1894, however, that the government began to take steps in response to the Governor’s proposal. On
this day, the Interior Minister (Kaoru Inoue, Foreign Minister in 1885), under the name of the Director of
the Prefectural Affairs Bureau of the Interior Ministry (Kazuyuki Egi), sent an inquiry to the Governor of
Okinawa Prefecture regarding following matters: (1) configuration of the harbors of the relevant islands;(2) prospect of local production and land development; (3) evidence that the islands belonged to Japanin ancient times, such as old records and oral traditions; and (4) existing relationship with Miyakojima
Island, Yaeyama Islands, and other islands.
In response to the aforementioned inquiry, on May 12, 1894, the Governor of Okinawa Prefecture
responded, “There exist no old records regarding the relevant islands or any transcribed evidence or oral
traditions which prove the islands belonged to Japan. The only relation is that fishermen in Okinawa
Prefecture, since ancient times, have sometimes sailed from Yaeyama Islands to the Nanto Islands(southern islands) to conduct fishing and hunting.”
After this response, we cannot find any official documents concerning this issue for some time
thereafter. The next official document appeared seven months later on December 15, which was later
submitted to a Cabinet meeting. This document attached a proposal to erect national markers, and its
main text explained the reasons for submitting it to the Cabinet meeting. It gave the following threereasons, namely: (1) the circumstances are significantly different in 1885 and today; (2) according to anoral statement of the officials of the Hydrographic Department of the Navy Ministry, Uotsuri Island andKuba Island have never been territories of any state; and (3) geologically, it can be considered as part of
the Okinawa Islands.
On December 27, more than ten days after the above document was prepared, the Interior Minister

5

(Yasushi Nomura) consulted the Foreign Minister (Munemitsu Mutsu) on bringing this issue before
the Cabinet meeting. In a letter dated January 11, 1895, the Foreign Minister responded that he had noobjections on it. On January 12, the Interior Minister requested the Prime Minister (Hirobumi Ito) toconvene a Cabinet meeting, and on January 14, the Cabinet decided as follows with regard to this matter:
Regarding the matter submitted by the Minister of Home Affairs for deliberation: In recent years,
certain persons have sailed in the direction of uninhabited islands known as Kuba and Uotsuri situated northwest of the Yaeyama Islands of Okinawa Prefecture with the intent to engage in fishingand other activities. Given the need to control such activities, there is no hindrance to determiningthat the said islands come under the jurisdiction of Okinawa Prefecture and permitting the erectionof jurisdictional markers as requested in the petition of the Okinawa Prefectural Governor.

III. Effective Control
The survey conducted by the Izumomaru in 1885 affirmed Japan’s intention of extending its sovereignty
over the Senkaku Islands through the dispatch of central and local government officials. At the sametime, it signified the first display of Japan’s effective control over the islands prior to their incorporation
into its territory.
Even if it is not “effective control” in the sense of international law, private citizens also launched thedevelopment of the Senkaku Islands on a full-fledged basis already from 1885. In 1884, Tatsushiro Koga
dispatched people to explore the islands and report on their current conditions. In 1885, he collected forthe first time products, such as bird feathers and marine products. Discovering that these products held
promise as exports and for creating domestic demand, Koga began to continuously collect such products
for business purposes.
In 1894, designing a plan to develop the islands, Koga submitted an application to the Governorof Okinawa Prefecture for permission to develop the Senkaku Islands. In June 1895, Koga also filed
Kanyuchi Haisyaku Negai, [Application for Leasing State-owned Land] with the Interior Minister. Koga’s
application for leasing state-owned land was formally accepted by the Interior Minister in August of thefollowing year, 1896.
The government accepted Koga’s application following the Cabinet decision to place Uotsuri Island
and another island under the jurisdiction of Okinawa Prefecture on January 14, 1895, and their incorporation into Yaeyama County, Okinawa Prefecture in April 1896. The Interior Minister granted Koga
approval to lease Uotsuri Island and Kuba Island free of charge for 30 years. From then on, Koga’s use of
the Senkaku Islands became no longer simply an act of a private citizen, but a state-authorized act that
constituted effective control under international law.
From 1918, Koga’s businesses were carried on by his son, Zenji Koga. The free lease of the islands expired in 1926, and subsequently, the islands were leased for a fee, subject to yearly contract. In 1932, Koga
applied for the purchase of Uotsuri Island, Kuba Island, Minamikojima Island, and Kitakojima Island,
and the government sold them off. The four islands thus became the private property of Koga. After
ownership was transferred and registered, Koga paid land tax for the four islands every year thereafter.
Tatsushiro and Zenji Koga engaged in diverse businesses on the islands. In addition to collecting
albatross feathers and mining guano, they carried out businesses such as processing shark fins, shellfish
and tortoise shells; canning seabirds; stuffing brown boobies and common terns; producing dried bonito;
and harvesting coral. In parallel with these businesses, the Koga built houses, reservoirs, wharves, andpiers on Uotsuri and Kuba Islands. They also improved sanitary facilities, such as drainage, protected sea

6birds, conducted test cultivation, such as of bananas, sugarcane, sweet potatoes, and tobacco, and planted
trees, such as cedar.
At least 2,000 laborers in total, fishermen, craftsmen, and others settled or were dispatched to the
Senkaku Islands over the period until Kogas’ businesses on the islands came to an end shortly before theoutbreak of the Pacific War. According to a report submitted by Tatsushiro Koga to the Interior Ministryin 1909, there were a total of 248 settlers, 90 houses, and over 60 chobu (approximately 595,020 m2) ofcleared land on the Senkaku Islands in 1907.
The development of the islands by Tatsushiro Koga after 1896 alone demonstrates that Japan displayed sufficient effective control for establishing its sovereignty over the Senkaku Islands. In addition
to this fact, Japan exercised state functions (sovereign acts) over the Senkaku Islands as explained below.
In 1896, the government designated the four islands of Uotsuri Island, Kuba Island, Minamikojima
Island, and Kitakojima Island as state-owned lands and registered as such in the State Register (under
the jurisdiction of the Interior Ministry). At the same time, based on this measure, the government
approved the lease of Uotsuri and Kuba Islands to Koga in August 1896. In regard to the incorporation of
the Senkaku Islands into the local administration system, following the Cabinet decision to incorporate
the Senkaku Islands into Okinawa Prefecture on January 14, 1895, the measures was taken to place themunder the jurisdiction of Yaeyama County of Okinawa Prefecture in April 1896. In December 1902,
the jurisdiction of the islands was conferred to Tonogusuku Village, Ohama District of Ishigakijima
Island (Yaeyama County). In December of the same year, the Provisional Land Survey Office of Okinawa
Prefecture conducted the first land measurement of the islands and made accurate scale maps of eachisland. Based on these measurements, the four islands, including Uotsuri Island, were formally listed
in the land register of Ishigakijima Island and were given address numbers. Later, land measurementsof the islands were conducted by the National Hydrographic Bureau in 1915, the Navy’s Hydrographic
Department in 1917, and the Forestry Bureau of Okinawa Prefecture in 1931.
Many other activities were also conducted on the Senkaku Islands, such as resource surveys and academic research which were approved or encouraged by national or local governments, rescue measures,and preliminary survey for the construction of a meteorological station. In 1900, 1901, 1903, and 1907,
national and local government officials (e.g. prefectural officials, prefectural engineers, and Yaeyama
police chief) sailed to the islands to conduct technical guidance, to observe the situation, and for otherpurposes. In 1932, a natural resources surveying team of the Ministry of Agriculture and Forestry was
assigned to the islands to conduct research. This surveying team, accompanied by Tsutomu Masaki fromthe Ishigakijima Island Meteorological Station, later submitted a report of the results. In 1940, when
the Greater Japan Airways aircraft “Aso” connecting Japan and Taiwan made an emergency landing in
Uotsuri Island, police officers from the Yaeyama Police Office and others rushed to the scene to rescue
the 13 passengers aboard. In 1943, at the request of the military, two engineers from the Ishigakijima
Island Meteorological Station visited Uotsuri Island in order to establish a meteorological station on theisland. Additionally, in 1945, police officers and military personnel went to Uotsuri Island to conduct
rescue activities associated with the wreckage of vessels that were carrying civilians evacuating to Taiwan.
On November 22, 1909, the government bestowed Tatsushiro Koga with the Medal with Blue Ribbon for
his achievements related to the development of the Senkaku Islands. On August 19, 1907, the Fukuoka
Mining Supervision Office formally approved Koga’s application for the mining of phosphate.
As the above facts demonstrate, before World War II, Japan had already exercised sufficient effective control for establishing sovereignty over the Senkaku Islands. After WWII, the Senkaku Islands
were placed under the legislative, judicial, and administrative control of the United States along with the7Nansei Shoto Islands south of 29˚ N latitude, including the Ryukyu Islands and Daito Islands (however,Amami Gunto were excluded after December 25, 1953).
Article 3 of the San Francisco Peace Treaty, which stipulates the administrative rights of the UnitedStates over the Nansei Shoto Islands, does not explicitly refer to the Senkaku Islands. However, it was clearthat the islands were included in the scope of Article 3 of the Peace Treaty from various sources, including U.S. Civil Administration Ordinance No. 68 (Provisions of the Government of the Ryukyu Islands) of
February 29, 1952 and U.S. Civil Administration Proclamation No. 27 (Geographical Boundaries of the
Ryukyu Islands) of December 25, 1953. Furthermore, the Senkaku Islands are listed with their individualnames of the islands in the “List of the Nansei Shoto Islands,” prepared by the Ministry of Foreign Affairsof Japan pursuant to the “Governmental and Administrative Separation of Certain Outlying Areas fromJapan” memorandum of the General Headquarters (GHQ), the Supreme Commander for the AlliedPowers (SCAP) dated January 29, 1946.
Article 3 of the Peace Treaty gave the United States only administering right over the Nansei Shoto
Islands south of 29˚ N latitude. Sovereignty over the Nansei Shoto Islands, including the Senkaku Islands,
remained in Japan. In the sense that Japan could not exercise territorial sovereignty over its territories of
the Nansei Shoto Islands, Japan was considered to have residual sovereignty over this area. On August 31,
1970, Mr. Robert J. McCloskey, Spokesperson of the U.S. Department of State, confirmed this point by
explicitly referring to the Senkaku Islands. This policy of the U.S. government remained consistent until
the reversion of Okinawa to Japan.
The Senkaku Islands were included in the scope of Article 3 of the San Francisco Peace Treaty.
As a result, the treaty ensured the legal status of the Senkaku Islands (that the islands were part of theterritory of Japan). Thus, it does not affect the attribution of the title of the islands the extent to which
the United States exercised administrative rights over the Senkaku Islands during the period that it had
administrative right.
Apart from the issue of the attribution, however, it can be said that the United States exercised
effective control (exercised administrative rights) over the Senkaku Islands in place of Japan after WWII
pursuant to Article 3 of the Peace Treaty. Although the United States did not exhibit the same degreeof effective control over the islands as Japan did before WWII, it was not zero, neither the U.S. Civil
Administration utilized Taisho Island, a state-owned land of the Senkaku Islands, as a Navy exercise
area after 1956 and Kuba Island, a private-owned land, as an Air Force exercise area in 1955 and as a
Navy practice area afterward. Since Kuba Island was private-owned land, the Basic Leasing Contract was
concluded on July 1, 1958 between the landowner, Zenji Koga, and the Ryukyu government as the agent
for the U.S. Civil Administration. According to this contract, the U.S. Civil Administration paid a certain
amount every year as a fee for utilizing the land for military purposes. The Ryukyu government had been
levying a fixed asset tax for the four islands Koga owns before the conclusion of the leasing contract, andthereafter it also collected withholding tax on the revenue that it collected from the rent.
Meanwhile, on March 5, 1955, the Legislature of the Ryukyu Government adopted a resolution calling for investigation by the U.S. Civil Administration, the Japanese government, the UN, among otherentities on the so-called Daisan Seitoku Maru Case. This was an incident of March 2, 1955 in which an
Okinawa fishing boat was subjected to gunshots from two junks of unidentified nationality in territorial
waters near Uotsuri Island and three crew members went missing. On October 28, 1967, the Ryukyu
government paid relief funds to the affected families in connection with this incident.
In 1961, Ishigaki City, which has administrative jurisdiction over the Senkaku Islands, sent officials to the islands to conduct a survey for reassessing fixed assets in accordance with the Land Rent

8

Stabilization Act. In May 1969, Ishigaki City, accompanied by the mayor, erected administrative markers
specifying the city’s jurisdiction on the five Senkaku Islands. At the same time, after 1968, the U.S. Civil
Administration and the Ryukyu government took various measures to control illegal entry into the islands. They included patrols by military aircraft, the construction of warning signs, patrols by the patrol
vessels of the Ryukyu government, and the issuance of exclusion orders against illegal entrants.
Five academic surveys on the Senkaku Islands were carried out after the war, even before thecommencement of the UN ECAFE survey on the East China Sea continental shelf. Academic, natural
resource, water quality and other research were conducted in 1950, 1952 (twice), 1963, and 1968 by various entities, such as University of the Ryukyus, the Meteorological Agency of the Ryukyu government,
the Yaeyama Local Government Office, the Yaeyama Meteorological Observatory, and the Ishigaki City
Police.

IV. Chinese and Taiwanese Arguments for the Title and Critiques against Them
The Government of the Republic of China (Taiwan) and the Government of the People’s Republic ofChina (China) asserted the title of the Senkaku Islands in the official foreign ministry statements on
June 11, 1971 and December 30, 1971, respectively. Since then, the issue of sovereignty over the Islands
has gained a feature of an international dispute between Japan, China, and Taiwan. Although China
and Taiwan formally make separate territorial claims, with each asserting that the islands are part oftheir own territory, the two share the view that the Senkaku Islands were part of the territory of China
prior to their incorporation into Japanese territory. Nevertheless, the arguments for the title by the two
are not necessarily the same. A number of differences are found in the way that the two states develop
their argument. This paper does not examine the differences unless it is necessary to do so. Instead, it
undertakes a holistic examination of the arguments that the islands are part of the territory of China andmakes a few critiques against these arguments.
In general, the arguments that the islands are part of the territory of China may be classified into thefollowing six categories. The first line of argument is based on historical documents, such as the recordsof Sakuhousi, investiture missions. The second is the assertion that Diaoyutai Senkaku Islands and otherislands were included in “The Island of Formosa together with all Islands appertaining or belonging to
the said Island of Formosa” in Article 2 of the Treaty of Shimonoseki. The third is the following assertions:
China discovered the islands since the names of Diaoyutai and other islands are found in the historical
documents of the Ming Dynasty; and China occupied the island of terra nullius before Japan since animperial edict of Empress Dowager Cixi of 1893 (the 19th year of Emperor Guangxu) serves as evidence
for China’s intention of extending its sovereignty to Diaoyutai and other islands or an act of its sovereign
power over the islands. The fourth line of argument is based on the geographical proximity as well as thegeological integrity between Taiwan and Diaoyutai and other islands. The fifth line of argument points
out the use of Diaoyutai and other islands by Taiwanese fishermen and the status of their use. The sixth
argument considers Diaoyutai and other islands as part of the continental shelf.
Of the above reasons and arguments, the forth through the sixth lines hardly pose any issues
under international law. It is clear from state practices and international precedents that geographicalproximity and geological integrity do not determine the attribution of sovereignty. Furthermore, theargument that the islands are part of the continental shelf ignores the definition of continental shelfunder international law. With regard to the use of the islands and their territorial waters by Taiwanesefishermen, even Taiwanese scholars of international law have found that these activities took place after
Japan’s rule of Taiwan. The use of the islands by Taiwanese fishermen and others during Japan’s rule of9Taiwan was done in compliance with Japan’s domestic laws at the time. Under the Nationality Act, suchactivities constituted activities of Japanese nationals. In addition, with respect to the use of the islands by
Taiwanese fishermen after WWII, even if the issue of its unlawfulness is left aside, this act was no morethan a simple act of a private citizen and does not give Taiwan any legal effect to claim sovereignty underinternational law. With regard to the work of dismantling submerged ships that Taiwanese laborers andothers conducted on the Senkaku Islands (including some activities to construct facilities on the islands),
after the U.S. Civil Administration began to regulate these activities, the work was continued throughprocedure to obtain a visa from the U.S. High Commissioner to enter the islands.
As regards the third line of argument concerning the imperial edict of Empress Dowager Cixi, there
are not only some questions over its credibility, such as its seal is not an official one, but also it reveals
the fact that there exists no evidence demonstrating China’s effective control other than the edict. Even
if the imperial edict were authentic, opinions are divided among Taiwanese scholars of internationallaw as to whether or not the edict should be regarded as evidence of effective control. It is believed that
Empress Dowager issued this imperial edict in order to award three islands, including Diaoyutai, to
Sheng Xuanhuai for the collection of medicinal herbs. However, Taiwanese newspapers and other sources have revealed that Sheng Xuanhuai himself never went to Diaoyutai or the other islands. On the other
hand, Japan had already exercised sovereignty over the Senkaku Islands eight years prior to the imperial
edict of Empress Dowager Cixi (in 1885, the Governor of Okinawa Prefecture dispatched Izumomaru
to conduct a survey of the islands after obtaining the consent of the Interior and Foreign Ministers andreceiving the government’s order regarding the islands survey). Therefore, the edict does not weaken
Japan’s territorial claims, regardless of whether or not it is credible.
With respect to Article 2 of the Treaty of Shimonoseki, the issue that was on the table at the peace
conference was whether or not the islands off the coast of Fujian Province were included in the islands
appertaining to Taiwan. The Qing Dynasty requested that the treaty specify the names of the islands
covered, fearing that Japan would assert even the islands close to Fujian Province included in the islands
appertaining to Taiwan. However, Japan explained that the Qing Dynasty’s concerns would never happen
so long as the Pescadores Islands were lying between Taiwan and Fujian Province, and the Qing delegatesgave their consent. As this background indicates, it was the islands off the coast of Fujian Province that
the Qing Dynasty expressed its concerns over the scope of the islands appertaining to Taiwan.
While the Treaty of Shimonoseki identifies the latitudes and longitudes of the Pescadores Islands,
which were considerably closer to Taiwan than the Senkaku Islands, the treaty neither names the Senkaku
Islands nor refers to their latitudes and longitudes. The Senkaku Islands obviously were not raised at allin the discussions at the peace conference. It is quite natural that the state parties did not question about
the Senkaku Islands as well as the three islands of Mianhua, Huaping, and Pengjia during the conference.
That is to say, in Volume 1 “Boundaries” of Zhuluo xianzhi [Zhuluo County Gazetteer], compiled by
Zhou Zhongxuan in 1717, Da Jilong Shan (current Keelung Port) is indicated as the northern boundary of
Taiwan Province (northern Taiwan). In “Boundaries” in Volume 1 “Border Gazetteer” of Danshui tingzhi[Danshui Sub-prefecture Gazetteer] compiled by Chen Peigui in 1871, Da Jilong Shan is similarly indicated as the endpoint of the far north road. Additionally, Keelung shizhi [Keelung City Gazetteer] editedby the Keelung City Historical Document Commission in 1954 states that the three islands of Mianhua,
Huaping, and Pengjia were incorporated into the administrative coverage of Taiwan Province in 1905
(the 31st year of Emperor Guangxu) and that in the same year the Japanese government rearranged thejurisdictional divisions. Taiwan sheng difang zizhi zhiyao “The Outline of the Local Self-Government in
Taiwan Province” published in 1965 also reaffirms that Pengjia and other islets were incorporated into the10coverage of Taiwan Province during Japan’s rule of Taiwan. By extension, as would be expected, various
sources, including the two official documents above and Zhonghua Minguo Nianjian “The Yearbook of
the Republic of China” published in 1968, explain that the northern limit or the extreme north of Taiwan
Province after the end of WWII is not the Senkaku Islands but Pengjia Island, which is approximately
150 km closer to Taiwan.
As observed from the above, at the end of the First Sino-Japanese War, the northern limit of Taiwan
Province for administrative purposes was Keelung Mountain. Neither the Senkaku Islands nor even thethree islands such as Pengjia were treated as islands appertaining to Taiwan Province. It was to be expected that the Senkaku Islands were not disputed during the Sino-Japanese peace conference.
Lastly, there are the archives, such as the records of investiture missions. The ones cited as supporting China’s territorial claims include: Shi Liuqiu lu [Records of the Imperial Missions to Ryukyu] byChen Kan (1534); Riben yijian [A Mirror of Japan] by Zheng Shungong (1556); Chong bian shi Liuqiu
lu [Recompilation of Records of the Imperial Mission to Ryukyu] by Guo Rulin (1561); Chou hai tu
bian “An Illustrated Compendium on Maritime Security” by Zheng Ruozeng (1562); Shi Liuliu zalu
[Miscellaneous Records of the Imperial Mission to Ryukyu] by Wang Ji (1682); Zhongshan Chuanxin
lu [Records of Messages from Chong-shan] by Xu Baoguang (1719); Liu Qiu Guo Zhi Lue [Annals of
Ryukyu] by Zhou Huang (1756); and Sangoku Tsuran Zusetsu [Illustrated Outline of the Three Countries]
by Shihei Hayashi (1785).
With regard to the records of Chen Kan, the controversial passage is that “In the evening of theeleventh day, Gumi Shan [Gumi Mountain, or Kume Island] came into view. The island belongs to
Ryukyu.” Similarly, it is also disputed the passage in Guo Rulin that “Chi Yu is the island that marks theboundary of the Ryukyu region.” According to China’s explanation, Chen Kan’s records explain indirectlythat islands lying closer to China from Kume Island were part of the territory of China, and furthermore,it can be construed from Guo Rulin’s records that Chi Yu (Sekibi-sho Island/Taisho Island) is an island
dividing the border of China and Ryukyu. Similarly, by interpreting “boundary between the inner andouter” in the records of Wang Ji and others to mean the boundary between China and other countries,
China explains that the border between China and Ryukyu was located in the waters between Chi Yu
and Kume Island.
This paper has already discussed why the above contentions are contrary to the facts. The threeislands of Mianhua, Huaping, and Pengjia were incorporated as islands appertaining to Taiwan for administrative purposes after 1905. Thus, it cannot be asserted that the China-Ryukyu border jumped
over these islands and was located in the waters between Chi Yu and Kume Island. In order to makethis assertion or interpretation plausible, one needs to assume that Taiwan together with these threeislands was already part of Chinese territory at the time of Chen Kan and Wang Ji in 16th century. The
first time that Taiwan was included in Chinese territory was, however, in the 22nd year of Kangxi, 1683.
This is evident in the official documents of the Qing Dynasty, including Taiwan fu zhi [Gazetteer of
Taiwan Prefecture] compiled by Gao Gongqian in 1696 and Xu xiu Taiwan fu zhi [Continued Gazetteerof Taiwan Prefecture] compiled by Yu Wenyi in 1765 (however, Taiwan fu zhi writes that Taiwan was
included in Chinese territory in the 20th year of Kangxi, 1681, stating that “Taiwan was included in
Chinese territory for the first time in the 20th year of Kangxi”).
Accordingly, it is a complete mistake to interpret historical documents earlier than Wang Ji records,
in the manner described above. Even historical documents of later times cannot be interpreted as such,as the three islands, including Pengjia Island, were not islands appertaining to Taiwan. The claim that the
Diaoyutai and other islands were painted in the same color as China in Sangoku Tsuran Zusetsu as well11

as the interpretation that the Diaoyutai Islands were islands appertaining to Taiwan on the basis of thepassage in Riben yijian “Diaoyu Yu is a small island belonging to Taiwan” ignore the facts. The assertion
that Diaoyutai and other islands were considered to be part of the territory of China because the islands
can be found in the “Map of the Coast of Fujian Province” in Chou Hai Tu Bian ignores or overlooks thefact that Volume 1-17 “Fujian Boundary” in Chou Hai Tu Bian does not depict Xiao Liuqiu (Taiwan),
Diaoyutai, and other islands (Pengjia Island-Pescadores Islands was depicted).
From all the historical documents cited in order to historically verify Chinese sovereignty, it fails
to prove China’s intention of extending sovereignty over the Senkaku Islands. In all of the citations concerned, China no more than attempts to verify its intention of extending sovereignty by its interpretationof the text of historical documents or the colors used in maps, while ignoring the facts, and furthermore,intermixing speculations and subjective views.

V. Conclusion
Many of the historical documents that refer to the Senkaku Islands are Chinese documents. Historical
documents from Japan and Ryukyu are generally limited to the aforementioned Sangoku Tsuran Zushi by
Shihei Hayashi, along with Chuzan Seikan [Mirror of Chuzan] by Choshu Haneji (Shoken Sho) (1650)
and “Shinan Kogi [Guide to Navigation] by Chobun Nago (Junsoku Tei) (1708). Chuzan Seikan no morethan reproduced the content of Chen Kan’s records and it has also been revealed that Shihei Hayashi’s
Sangoku Tsuran Zushi relies on Zhongshan Chuanxin lu by Xu Baoguang. Therefore, it is sometimes
alleged from these facts that the Chinese were the first to discover the Senkaku Islands and that the
Ryukyu people had no other way of knowing the existence of the Senkaku Islands other than through
Chinese people or Chinese literatures.
This reasoning, however, merely compares the number of sources and jumps to conclusions. As isrevealed also in Chen Kan’s records, it was the Ryukyu people who were deeply familiar with the navigation route around the Senkaku Islands. Chinese people, who were unfamiliar with the navigation route,could make their way to the Ryukyu only with the pilot of the Ryukyu people aboard Chinese investiture
ships. Ryukyu and China had an investiture and tribute relationship for 496 years from 1372 to 1868.
Despite this length of time, Chinese investiture ships sailed to Ryukyu no more than 23 times. Although
this equates to once every 21.5 years by simple calculation, in reality, intervals of 30 or 40 years were notrare. In particular, no ships sailed over a 55-year interval between Chen Kan and his predecessor, envoy
Dong Min.
In contrast, the Ryukyu Kingdom dispatched tribute ships to Fuzhou every year from 1372 to 1523,
except for a 32-year interval in between. After the once-a-year tribute system was abolished in 1523,
tribute ships did not sail to China every year but a considerable number of ships were still dispatched.
Ryukyu dispatched to Fuzhou not only tribute ships but also ships for various other purposes, including
appreciation ships, reception ships, and escort ships. On their return to Ryukyu, the ships took routes
that passed the Senkaku Islands. Their trips total 240, counting only the trips for which records still exist.
In addition, Ryukyu ships are believed to have taken the routes along the Senkaku Islands on their return
trips from trade activities with southern areas. If these trips are added, the number of trips exceeds 330.
Moreover, trade between Ryukyu and the southern areas had begun in around the early 14th century,
prior to the commencement of the investiture relationship with China.
The navigation routes along the Senkaku Islands can be heavily affected depending on the seasonal
winds. Even if the literature does not record whether or not the navigation route along the Senkaku
Islands was taken, the dates on which a Ryukyu ship left and entered a port are recorded. Furthermore,

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records indicate that these dates fall around the same season. This is the same season that investiture
ships left the port in Fuzhou. From Ryukyu’s perspective, the navigation route along the Senkaku Islands
was the shortest return route from trade activities with southern areas; while for investiture ships, it
was an indirect route between Ryukyu and Fuzhou. It is well documented in Omorosaushi (compilationof Ryukuan songs from 1531 to 1623) and other sources that Ryukyu Kangoufu ships (trading ships
certified by the Ming government) utilized the seasonal wind of the south wind to return to Ryukyu uponcompleting their trade activities with southern areas. Chen Kan’s records do not state that Chen Kan
himself discovered or named the Senkaku Islands. It can neither be deemed that Chen Kan knew theirnames from earlier literatures. There is no trace of such literature being cited in Chen Kan’s records, nor
is there indication that he gave names to the islands.
It seems that Chen Kan learned of the names of the Senkaku Islands aboard an investiture ship. It
is also presumed that Min people (people from Fuzhou) were not aware of their names since they were
unfamiliar with the routes passing the Senkaku Islands, as described in Chen Kan’s records. In reality,
those who took the route to the Senkaku Islands were not Min people but were Ryukyu people who wereaboard Chen Kan’s investiture ship. As these islands were the navigation marks of the route, it is possible
to think that Ryukyu people had given names to the islands as a means of distinguishing the marks. It
may be more natural and accurate for Chen Kan to ask Ryukyu people aboard the ship the names of theislands.

Reference
A list of the author’s other works is provided below for reference purposes:“Senkaku Retto: Rekishi to Seiji no Aida” [The Senkaku Islands: Between History and Politics], Nihon
oyobi Nihonjin [Japan and the Japanese] (January 1970).
“Senkaku Retto no Hoteki Chii” [The Legal Status of the Senkaku Islands], Kikan Okinawa [Okinawa
Quarterly], Vol. 52 (March 1970).
“Senkaku Retto: Sono Hoteki Chii” [The Senkaku Islands: Their Legal Status], Okinawa Times (September
2-9, 1970).
“Senkaku Retto no Ryouyuken Mondai” [Territorial Issues of the Senkaku Islands], Kikan Okinawa[Okinawa Quarterly], Vol. 56 (March 1971).
“Senkaku Retto no Ryouyuken to Meiho Ronbun” [Sovereignty over the Senkaku Islands and Ming Pao
Essay], Chugoku [China] (June 1971).
“Senkaku Retto Ryouyuken no Houri” [Doctrines Behind Sovereignty over the Senkaku Islands], Nihon
oyobi Nihonjin [Japan and the Japanese] (January 1972).
“Senkaku Retto to Ryoudoken Kizoku Mondai” [The Senkaku Islands and the Issue of the Attribution ofSovereignty], Asahi Asia Review, Vol. 2 (1972).
“Senkaku Retto to Royuken Mondai” [The Senkaku Islands and the Issue of Sovereignty], Sunday
Okinawa Shukan [Sunday Okinawa Weekly] (96 installments from July 8, 1872 to June 15, 1974).
“Ugokanu Senkaku Retto no Ryouyuken” [Unchanging Sovereignty over the Senkaku Islands], Nihon
oyobi Nihonjin [Japan and the Japanese] (January 1973).
“Senkaku Retto Mondai to Inoue Kiyoshi Ronbun” [The Senkaku Islands Dispute and the Kiyoshi Inoue
Paper], Asahi Asia Review, Vol. 1 (1973).
“Mindai oyobi Shindai ni okeru Senkaku Retto no Hoteki Chii” [The Legal Status of the Senkaku Islandsin the Ming and Qing Dynasties], Kikan Okinawa [Okinawa Quarterly], Vol. 63 (December 1972).
“Senkaku Retto no Ryodo Hennyu Keii” [Background of the Territorial Incorporation of the Senkaku

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Islands], Seikei Gakkai Shi (Kokushikan Daigaku) [Journal of Politics and Economics (Kokushikan
University)], Vol. 4 (February 1975).
“Senkaku Retto wa Chugoku no Ryoudo dewa nai” [The Senkaku Islands Are Not Chinese Territory], 20
Seiki [20th Century] (June 1978).
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Koron (July 1978).
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Japanese Territory], Ho to Chitsujo [Law and Order], Vol. 8, No. 5 (October 1978).
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the Grounds for Chinese and Taiwanese Territorial Claims], AFA Series, Vol. 6 (Asia Friendship
Association) (December 1978).
“Senkaku Retto (Ge): Nihon no Ryoudo Hennyu Sochi” [The Senkaku Islands (Part 2): Incorporation
into Japanese Territory], Ho to Chitsujo [Law and Order], Vol. 8, No. 6 (December 1978).
“Senkaku Retto to Nihon no Ryouyuken: Ryoudo Hennyu no Shiteki Kosatsu” [The Senkaku Islands andJapan’s Sovereignty: Historical Examination of Territorial Incorporation], Junkan Sekai to Nihon[Trimonthly Magazine, World and Japan], Vol. 234 (April 15, 1979).
“The Territorial Sovereignty over the Senkaku Islands and Problems on the Surrounding Continental
Shelf,” Japanese Annual of International Law, No. 15 (1971).

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