Matsumae clan
Upon adoption of the 1947 constitution, the Empire of Japan dissolved and became simply the state of Japan, and all overseas territories were lost. Japan was reduced to the territories that were traditionally within the Japanese cultural sphere pre-1895: the four main islands (Honshu, Hokkaido, Kyushu, and Shikoku), the Ryukyu Islands, and the Nanpō Islands. The Kuril Islands also historically belonged to Japan and were first inhabited by the Ainu people before coming under the control of the Matsumae clan during the Edo Period. However, the Kuril Islands were not included due to a dispute with the Soviet Union.