一都三県

• 1都3県

Of 一(いち) (ichi) + 都(と) (to) + 三(さん) (san) + 県(けん) (ken), literally “one to three ken”, in reference to Tokyo (東京都(とうきょうと) (Tōkyō to)), Kanagawa, Chiba, and Saitama (県(けん) (ken)) prefectures.

• IPA^(key):

一(いっ)都(と)三(さん)県(けん) • (Itto sanken) 

1. the Tokyo metropolitan region; the area surrounding and including the capital of Japan in Eastern Tokyo
   • 1977, Asahi Shimbun, Keizai taikoku no jirenma [Dilemma of economic super powers], volume 3, page 6:

     東(とう)京(きょう)・千(ち)葉・埼(ば・さい)玉(たま)・神(か)奈(な)川(がわ)の一(いっ)都(と)三(さん)県(けん)が「地(じ)盤(ばん)沈(ちん)下(か)は荒(あら)川(かわ)河(か)口(こう)から北(きた)関(かん)東(とう)にかけ、数(すう)百(ひゃく)年(ねん)間(かん)にたまった地(ち)下(か)水(すい)くみ上(あ)げ 」

     Tōkyō Chiba Saitama Kanagawa no Itto sanken ga “jibanchinka wa Arakawa kakō kara kita Kantō ni kake, sūhyaku nenkan ni tamatta chikasui kumi age ”

     According to Tokyo, Chiba, Saitama, and Kanagawa metropolitan officials, “Subsidence from the mouth of the Arakawa river to northern Kanto is the result of accumulated groundwater seepage over hundreds of years”

   • 2018 April 17, Ministry of Economy, Trade, and Industry, “Itto sanken ichi-shi ni okeru jisedai jidōsha sangyō bunya no renkei shien keikaku [Concerning support for coordinating an Itto sanken single market next generation automobile industry program]”, in Ministry of Economy, Trade, and Industry‎ (PDF), archived from the original on 2 November 2021:

     ①(いち)支( し)援(えん)対(たい)象(しょう)とする事(じ)業(ぎょう)分(ぶん)野(や)：1(いっ)都(と)3(さん)県(けん)1(いっ)市(し)における次(じ)世(せ)代(だい)自(じ)動(どう)車(しゃ)産(さん)業(ぎょう)分(ぶん)野(や)

     Ichi Shien taishō to suru jigyō bun'ya: Itto sanken isshi ni okeru jisedai jidōsha sangyō bun'ya

     1. Business field to be supported: Metropolitan area single market next-generation automobile industry

   • 2020 May 1, Tokyo Metropolitan Government, “Inochi no mamoru STAY HOME shūkan [Stay Home week to save lives]”, in Kanagawa Prefecture‎, archived from the original on 21 October 2021:

     こんにちは。一(いっ)都(と)三(さん)県(けん)は同(おな)じ危(き)機(き)意(い)識(しき)の下(した)、4(し)月(がつ)25(にじゅうご)日(にち)から5(ご)月(がつ)6(むい)日(か)まで、「いのちを守(まも)るSTAY(ステー) HOME(ホーム)週( しゅう)間(かん)」として、共(きょう)同(どう)キャンペーンを行(おこな)っています。

     Konnichiha. Itto sanken wa onaji kiki ishiki no shita, shigatsu nijūgonichi kara gogatsu muika made, “inochi o mamoru sutē hōmu shūkan” to shite, kyōdō kyanpēn o okonatteimasu.

     Good afternoon. With the entire metropolitan region under a sense of crisis, April 25 to May 6 is being jointly declared the “Stay Home to Protect Lives week” campaign.

   • 2021 February 2, “Itto sanken kyōdō jōmyō ni tsuite [Regarding the metropolitan area joint declaration]”, in Chiba Prefecture‎, archived from the original on 2 November 2021:

     緊(きん)急(きゅう)事(じ)態(たい)宣(せん)言(げん)が延(えん)長(ちょう)されたことを受(う)け、令(れい)和(わ) 3(さん)年(ねん) 2(に)月(がつ) 2(ふつ)日(か)（火(か)曜(よう)日(び)）に、埼(さい)玉(たま)県(けん)、千(ち)葉(ば)県(けん)、東(とう)京(きょう)都(と)、神(か)奈(な)川(がわ)県(けん)の一(いっ)都(と)三(さん)県(けん)知(ち)事(じ)は連(れん)名(めい)で共(きょう)同(どう)声(せい)明(めい)を発(はっ)表(ぴょう)いたしました。

     Kinkyū jitai sengen ga enchō sareta koto o uke, Reiwa san-nen nigatsu futsuka (kayōbi) ni, Saitama-ken, Chiba-ken, Tōkyō-to, Kanagawa-ken no Itto sanken chiji wa renmei de kyōdō seimei o happyō itashimashita.

     Following the extension of the state of emergency on Tuesday February 2, Reiwa 3 , the governors of Saitama, Chiba, Tokyo, and Kanagawa metropolitan area prefectures released the following joint statement.