The maximum extent including the home islands and the Japanese colonial empire was in 1942. After its defeat in World War II the empire was dismantled. The contemporary territories include the Japanese archipelago and these areas. Regardless of territorial changes the emperor remains the formal head of state of Japan. During most of history, de facto power was with shoguns or prime ministers. The emperor was more like a revered embodiment of divine harmony than the head of an actual governing administration. In Japan, it was more effective for ambitious daimyo (feudal lords) to hold actual power, as such positions were not inherently contradictory to the emperor's position. The shoguns and prime ministers derived their legitimacy from the emperor. The parliamentary government continues a similar coexistence with the emperor.
The maximum extent including the home islands and the Japanese colonial empire was in 1942. After its defeat in World War II the empire was dismantled. The contemporary territories include the Japanese archipelago and these areas. Regardless of territorial changes the emperor remains the formal head of state of Japan. During most of history, de facto power was with shoguns or prime ministers. The emperor was more like a revered embodiment of divine harmony than the head of an actual governing administration In Japan, it was more effective for ambitious daimyo (feudal lords) to hold actual power, as such positions were not inherently contradictory to the emperor's position. The shoguns and prime ministers derived their legitimacy from the emperor. The parliamentary government continues a similar coexistence with the emperor.