Annexation Korea was not Japan's objective but the result of complex process.

Japan's commitment to Korea had been motivated by the national security.
Two leaders of Imperial government, prime minister Ito Hirobumi and Chief of the staff Yamagata Aritomo were learned public administration from Lorenz von Stein in the University of Vienna. Stein taught them that it need to control adjacent area for guard main land. According to Stein's theory Ito and Yamagata thought it was need to exclude other major powers from Korea.

At first Japanese leaders tried to support Korean progressives. They thought if Korea modernized by themselves and become stabilized independent nation will be shield Japan from continental powers. But progressives were defeated in struggle with conservatives that they depends on China. Chinese minister Li Hongzhang had increased influence on Korea and planned annex Korea to China mainland. Empire declared war to China for guard Korea's independent.

Even after winning the war Japanese objective that stabilized east Asia by Korean independent was not achieved because Korean conservatives oppressed progressives. Frustrated Japanese diplomat and activist in Seoul allied with Korean progressive without consultation to Tokyo and raid the king's court. They killed the queen who lead conservatives but king escaped to the Russian embassy. By this stupid violence resulted the lose of Japanese influence and Russian power increase.

In the early of the 20 century Russia occupied Manchuria and had seemed they aimed Korea in the next. Ito proposed to Russia division of influence in the Korea but Russia ignored. After all, Japan started war with Russia.

By the victory of Russo-Japanese war, Japan had exclude other powers influence from Korea. But until this time Japan almost abandoned Yi dynasty of Korea as the political partner. Korean king had thought as if his nation is private property. Nobles had clinged on the traditional social system and hated modernization. Yamagata thought abolish incompetent Yi dynasty and thought direct governance of Korea by annexation.

Nowadays Ito is the most hated Japanese politician in Korea. But ironically Ito was the last politician oppose to annexation and the guardian of kingdom. He told annexation was financially burdensome and never economical benefit and tried to modernize Korean government under supervise of Japan. But Ito was too optimistic for the value of modern civilization and too insensitivity about Koreans identity and pride. His interference occurred resistance all over the Korea. His challenge had stuck and forced to approve Yamagata's policy. Soon after Ito was assassinated by Korean patriot annexation was achieved.