Title: Japan–Korea Agreement of August 1904
Content:  Yongampho." This treaty required Korea to engage financial and diplomatic advisers designated by Japan. Also, the treaty required Korea to consult with Japan before making treaties with foreign powers, and before granting concessions or making contracts with foreigners. The treaty presumes that the Envoy Extraordinary and Minister Plenipotentiary of His Majesty the Emperor of Japan and the Minister of State for Foreign Affairs ad interim of His Majesty the Emperor of Korea were respectively authorized and empowered to negotiate and to agree upon the specific language of the proposed bilateral treaty:  The Korean Government shall engage as financial adviser to the Korean Government a Japanese subject recommended by the Japanese Government, and all matters concerning finance shall 
Title: History of Japan–Korea relations
Content:  At the end of World War II, Korea regained its independence after 35 years of imperialist Japanese rule. Per the Yalta Conference agreements, Soviet forces accepted surrender of Japanese forces in northern Korea above the 38th parallel, and U.S. forces south of that line. Korea was then divided into Soviet (North Korean) and U.S. (South Korean) spheres. South Korea refused diplomatic and trade relations with Japan, using tensions with Japan to rally support for the South Korean government. The early ROK (Republic of Korea; South Korea) government derived its legitimacy from its opposition to Japan and North Korea, portraying South Korea as under threat from the North and South. The diplomatic relationship between Japan and South Korea was established in 1965, when the Treaty on Basic Relations was signed; Japan subsequently recognized the Republic of Korea (the official name of South Korea) as the only legitimate government on the Korean Peninsula. As such, North Korea does not have official diplomatic ties with Japan.
Title: Joseon–United States Treaty of 1882
Content:  In 1876, Korea established a trade treaty with Japan after Japanese ships approached Ganghwado and threatened to fire on the Korean capital city. Treaty negotiations with the U.S. and with several European countries were made possible by the completion of this initial Japanese overture. Negotiations with Qing were a significant feature of the process which resulted in this treaty. The Chinese played a significant role in the treaty negotiation, although Korea was an independent country at the time, which was explicitly mentioned in the treaty.
Title: Japan–Korea Agreement of April 1905
Content:  "shall deliver to the Korean Government a suitable percentage" of the profits. The treaty preamble asserted that the Envoy Extraordinary and Minister Plenipotentiary of His Majesty the Emperor of Japan and the Minister of State for Foreign Affairs of His Majesty the Emperor of Korea were "respectively duly empowered" to negotiate and to agree upon the specific language of the proposed bilateral treaty: The Imperial Government of Korea shall transfer and assign the control and administration of the post, telegraph and telephone services in Korea (except the telephone service exclusively pertaining to the Department of the Imperial Household) to the Imperial Japanese Government. The land, buildings, furnitures, instruments, machines 
Title: Japan–Korea Treaty of 1905
Content:  Following Imperial Japan's victory in the Russo-Japanese War, with its subsequent withdrawal of Russian influence, and the Taft–Katsura Agreement, in which the United States allegedly agreed not to interfere with Japan in matters concerning Korea, the Japanese government sought to formalize its sphere of influence over the Korean Peninsula. Delegates of both Empires met in Seoul to resolve differences in matters pertaining to Korea's future foreign policy; however, with the Korean Imperial palace under occupation by Japanese troops, and the Imperial Japanese Army stationed at strategic locations throughout Korea, the Korean side was at a distinct disadvantage in the discussions.
Title: Japan–Korea Agreement of August 1904
Content:  dealt with after his counsel has been taken. The Korean Government shall engage as a diplomatic adviser to the Department of Foreign Affairs a foreigner recommended by the Japanese Government, and all important matters concerning foreign relations shall be dealt with after his counsel has been taken. The Korean Government shall consult the Japanese Government previous to concluding Treaties or Conventions with foreign Powers, and in dealing with other important diplomatic affairs such as granting of concessions to or contracts with foreigners. An amplified explanation of the scope and purpose of Article III was mentioned in a 1904 letter from the Japanese Ambassador to the United States Takahira Kogorō to the American Secretary of State John Hay:
Title: Japan–North Korea relations
Content:  In the early 1990s, Japan conducted lengthy negotiations with North Korea aimed at establishing diplomatic relations while maintaining its relations with Seoul. In September 1990 Japanese political delegation led by former deputy Prime Minister Shin Kanemaru of the Liberal Democratic Party visited North Korea. Following private meetings between Kanemaru and North Korean leader Kim Il Sung, a joint declaration released on September 28 called for Japan to apologize and to compensate North Korea for its period of colonial rule. Japan and North Korea agreed to begin talks aimed at the establishment of diplomatic relations. In January 1991, Japan began normalization talks with Pyongyang with a formal apology for its 1910-45 colonial rule of the Korean Peninsula. The negotiations 
Title: History of Japan–Korea relations
Content:  Japan declared war on Russia to drive out Russian influence, while Korea declared to be neutral. Japan's victory in the Russo-Japanese War, the Japan–Korea Treaty of 1905 was agreed in which Korea became a colony of Japan. Japanese officials increasingly controlled the national government but had little local presence, thereby allowing space for anti-Japanese activism by Korean nationalists. The new status failed because of a combination of diverse economic, historical, and emotional factors. Japan underestimated Korean nationalism and the hostility with which Koreans reacted against the modernizing programs which Japan was introducing. Emperor Gojong, who did not accept the conclusion of this Treaty, dispatched secret envoys to the second Hague Peace Conference in 1907 in order to denounce the conclusion of the treaty as 
Title: Japan–South Korea Joint Declaration of 1998
Content:  An existing treaty between South Korea and Japan, the Treaty on Basic Relations between Japan and the Republic of Korea, was signed on June 22, 1965 and provided basic diplomatic relations for the two states. In this treaty, signed by Japanese PM Eisaku Satō and the South Korean dictator Park Chung-hee, Japan and South Korea agreed upon settling problems with property during war-time, individual claims for compensation, and economic cooperation. Japan provided South Korea with $800 million, which would settle any issues about Imperial-era property and compensation for individuals. On July 6, 1992, Chief Cabinet Secretary Koichi Kato made an apology towards South Korea and to the wartime comfort women. Kato touched upon the remorse that Japan feels, along with hopes to build “future-oriented” relations with South Korea. The "Murayama Statement", also called "On the occasion of the 
Title: Japan–Korea Treaty of 1876
Content:  The Japan–Korea Treaty of 1876 (also known as the Japan-Korea Treaty of Amity in Japan and the Treaty of Ganghwa Island in Korea) was made between representatives of the Empire of Japan and the Korean Kingdom of Joseon in 1876. Negotiations were concluded on February 26, 1876. In Korea, Heungseon Daewongun, who instituted a policy of closing doors to European powers, was forced into retirement by his son King Gojong and Gojong's wife, Empress Myeongseong. France and the United States had already made several unsuccessful attempts to begin commerce with the Joseon dynasty during the Daewongun's era. However, after he was removed from power, many new officials who supported the idea of opening commerce with foreigners took power. While there was political instability, Japan developed a plan to open and exert influence on Korea before a European power could. In 1875, their plan was put into action: the Un'yō, a small Japanese warship, was dispatched to present a show of force and survey coastal waters without Korean permission.

Question: who negotiated an agreement with japan concerning the future of korea?
Answer: the Korean Empire.
Empire of Japan.
Taft.
Korean Empire.