Tokyo 10th district is a constituency of the House of Representatives in the Diet of Japan (national legislature). It is located in Tokyo and covers northwestern parts of the former city of Tokyo. The district consists of the wards of Toshima and parts of Nerima. As of 2012, 351,821 eligible voters were registered in the district.
Before the electoral reform of 1994, the area had been part of Tokyo 5th district where three Representatives had been elected by single non-transferable vote.
The current representative for the 10th district, elected in a 2016 by-election, is former attorney Masaru Wakasa, previously unsuccessful proportional candidate for the House of Councillors and since 2014 proportional member of the House of the Representatives from the Tokyo block. Until her successful gubernatorial bid in 2016, Liberal Democrat Yuriko Koike had represented the district. Koike, formerly a representative for Hyōgo 6th district, had taken over Tokyo 10th district in 2005 as one of Jun’ichirō Koizumi's "female assassins" to take out postal privatization rebel Kōki Kobayashi. In the landslide election of 2009, she lost the district to Takako Ebata (DPJ, Ozawa group), one of the so-called "Ozawa girls" (小沢ガールズ, Ozawa gāruzu), a group of female first-time candidates handpicked by DPJ ex-chairman Ichirō Ozawa.