The idea of Japanese imperialism and their dominance started after the introduction of Meiji Restoration, a reform, renovation, revolution, and renew of the government system, and it brought the practical imperial rule in Japan in 1868. During the restoration, Japanese political system was returned to the Emperor Mutsuhito, and he seized military power from the Shogun and established new government. Direct imperial rule immediately became widespread, and citizens showed their loyalty to the Emperor. To catch up with western colonial power, Japan moved aggressively into other countries and continents. Within Japan, the new government aggressively go ahead with westernization and modernization. Through out the First Sino-Japanese War, Russo-Japanese War, Japanese Annexation of Korea, and the World War I, Japan gained their force and imperialized. A series of victories brought the conscious of being one of the leading countries, and Japan became the only major non-western colonial power. Japan pressed forward japanization, the idea of Japanese culture dominates and assimilation, in other Asian countries. On the other hand, when the World War II started, Japan was facing a shortage of military demand, thus they had to rely on their occupied territories to make up for those shortages. It was a turning point that Great East Asia Co-Prosperity Sphere became Japanese living space for continuing the war. .
Hong Kong was not an exception of Japanese pacific campaign. Forces of the Empire of Japan attacked Hong Kong, the same morning Japan attacked on Pearl Harbor in 1941. Hong Kong was a part of the British Empire and the only Far East colony and naval base they had. It had an important role to maintain a good relationship with other countries as a neutral country. Thus, Japan was not welcomed to let Great Britain colonize Hong Kong due to its important functioning in Asia. After Japanese Imperial Army captured Guangzhou, the city next to Hong Kong, they brought occupying Hong Kong into their view as part of a general Pacific campaign, and decided to utilize the place as military base.