Tōkyō 25th district is a constituency of the House of Representatives in the Diet of Japan. It is located in Western mainland Tokyo and covers, aside from the Izu and Ogasawara islands (part of the 3rd district), the most rural parts of the prefecture: the cities of Ōme, Fussa, Akiruno, Hamura and the Nishitama county. As of 2012, 321,319 eligible voters were registered in the district giving it the highest vote weight in Tokyo – several districts in former Tokyo city in Eastern Tokyo have more than 450,000 voters – but still more than 1.5 times as many voters as the least populated electoral districts in Japan.