Chôxen (朝鮮) is a former colony of Japan, covering the Korean peninsula. It was Japan's first overseas conquest. The first troops arrived in 1592, and within a few years had overrun the entire kingdom. It was divided into several provinces (kuni) governed by various daimyô. Chôxen was initially governed by a kind of governor-general, Katô Kiyomasa. That office was later abolished, and it was governed as simply a region of Japan.
Over the centuries, Japanese influence gradually assimilated the Choxenese, so that today Choxenese is a minority language (though the first official language), and the Choxenese that does remain is heavily influenced by Japanese.
During the First Global War, most of Chôxen fell under Chinese rule, Japan only retaining a small portion around Pusan. This lasted until the Third Global War, when Japan recaptured Chôxen, along with Manchuria and Mongolia.
Having been liberated from one imperial power, the Choxenese were unwilling to be simply returned to another imperial power, and the Japanese soon acknowledged them as a member-state of the Federation of Japanese States. The area around Pusan which had remained in Japanese control between the First and Third Global Wars resisted incorporation in the new State of Chôxen, and is instead governed as the Japanese dô of South Chôxen.