The Empire of Japan is a federal constitutional dyarchy. Its co-heads of state are the Emperor and the Tycoon.
Japan after the Keiō Restoration put considerable effort into modernization. In 1875, Japan signed the Treaty of Saint Petersburg with Russia, ceding control of Sakhalin in exchange for control of the Kurile Islands and the Aleutian Islands.
To the south, the Kingdom of Ryūkyū was annexed to the Empire, its king being demoted to daimy&333; in exchange for a peaceful annexation. In 1895, Japan and China went to war over Korea (the Sino-Japanese War). Japan was the overwhelming victor, and Korea became a Japanese protectorate. The Tycoon shortly afterwards copied the pattern successfully pioneered in his own nation with Korea, becoming likewise Tycoon of Korea, with the Korean Emperor as (nominally) co-head of state. China was forced to pay a massive indemnity of 200 million tael, and to cede control of Taiwan and the Pescadores. Initially, Japan demanded control of the Liaotung Penninsula, but in the so-called Triple Intervention, France, Germany, and Russia compelled Japan to withdraw that demand, in exchange for a greater indemnity.
With part of this indemnity, Japan purchased the Russian territory of Alaska. A few years later, gold was discovered.
Friction grew between Japan and Russia over Russia's annexation of Port Arthur, which Japan had been forced in the Triple Intervention to concede, and growing Russian influence in Korea and Manchuria. In addition, many Russians were unhappy over the discovery of gold in the recently-sold Alaska. This friction lead to the Russo-Japanese War. Japan crushed Russian forces, driving them out of Korea and Manchuria, and invading Russia proper. Shock at these defeats lead to the Russian Revolution of 1905. Japan continued their attack on Russia, while Russia desperately sought peace. Japan marched to the Urals with little effective opposition, setting up a puppet Republic of Siberia, successful beyond their wildest dreams. Japan was now recognized as a major Power.
Japan began to acquire greater control over Manchuria, and, during the European War, took advantage of the distraction of world attention by invading Manchuria and setting up a puppet Empire of Manchuria, with the deposed Emperor of China on its throne.
After the defeat of England and France in the European War, Japan began to seize their Pacific territories one by one, governing them either as outright colonies or as protectorates, such as the (restored) Kingdom of Hawai'i