The Empire of Japan (Dainippon Teikoku) is the central nation in the world-wide Federation of Japanese States (Wakokka Renmei). Japan is home of the Emperor, or Mikado, also called Tennô, who is the head of state of all Japanese Nations. Japan is the largest nation on Earth. Extending from the Ryukyu Islands in the south up through the Japanese archipelago, and into the Kuril Islands and Karafuto Island, and then up onto the Asian mainland to include a vast area of northeastern Asia, from the Obu-Iruchixi (Ob-Irtysh in Russian) river eastwards, and into northwestern North America.