Dai Nippon Teikoku
The Japanese Empire was formed by the Meiji Constitution of 1889 as a new government for Japan following the interim government of the Meiji Restoration. Its governmental structures, such as the Diet, are still seen in Japanese government today, although they were all heavily altered by SCAP in the late 1940's.
The Japanese Empire in 1938 consisted of Nippon (Japan), Chosen (Korea), Manchukuo (Manchuria), Dalian, Taiwan, the Caroline Islands, the Mariana Islands, the Kuril Islands, and the southern half of Sakhalin.
During the late 1930's, the Imperial military took control of Beijing, Qingdao, and a large portion of the Yangtze River valley including Shanghai and Nanjing. In 1940, they occupied French Indochina (now known as Vietnam), and extorted the allegiance of the king of Siam (now known as Thailand).
Following the attack on Pearl Harbor on December 7, 1941, the Japanese quickly invaded, defeated, and annexed Hong Kong, Burma (now known as Myanmar), Malaysia, the Dutch East Indies (now known as Indonesia), the Philippines, the northern half of New Guinea, the Solomon Islands, the Gilbert Islands, Wake Island, and Attu in the Aleutian Islands. This was as large as the Empire ever became.
Virtually all of Japan's possessions in Indonesia, Micronesia, and Melanesia were liberated by General Douglas MacArthur's island hopping campaign between 1943 and 1945. In the closing days of the war, the British liberated Burma, and the Russians liberated Manchuria and North Korea.
The Japanese Empire is also known as the Nipponese Empire and the Greater East Asia Co-Prosperity Sphere.