The National Diet is the national legislature of Japan. It is composed of a lower house, called the House of Representatives, and an upper house, the House of Councillors. Both houses are directly elected under a parallel voting system. In addition to passing laws, the Diet is formally responsible for nominating the Prime Minister. The Diet was first established as the Imperial Diet in 1890 under the Meiji Constitution, and took its current form in 1947 upon the adoption of the post-war constitution. Both houses meet in the National Diet Building in Nagatachō, Chiyoda, Tokyo.

Japan is an island country in East Asia. It is in the northwest Pacific Ocean and is bordered on the west by the Sea of Japan, extending from the Sea of Okhotsk in the north toward the East China Sea, Philippine Sea, and Taiwan in the south. Japan is a part of the Ring of Fire, and spans an archipelago of 14,125 islands, with the five main islands being Hokkaido, Honshu, Shikoku, Kyushu, and Okinawa. Tokyo is the country's capital and largest city, followed by Yokohama, Osaka, Nagoya, Sapporo, Fukuoka, Kobe, and Kyoto.