Yotsuya (四谷) is a neighborhood in Shinjuku, Tokyo, Japan. It is immediately adjacent to the Kojimachi area that falls within Chiyoda. Before 1943, when Tokyo was a city, Yotsuya was one of its wards. The name is written variously as 四谷, 四ツ谷, and 四ッ谷.
As a ward, Yotsuya had definite boundaries, but as a modern neighborhood, it is less clearly defined. An area within Shinjuku is named Yotsuya, divided into four chōme.
Before the growth of Edo, Yotsuya was a farming village outside the city. In 1634, with the digging of the outer moat around Edo Castle, many temples and shrines moved to Yotsuya. The moat had stone walls, and a mitsuke, or watch tower, was also built. Yotsuya Mitsuke stood near the present-day JR Yotsuya Station.
The relocation of the temples and construction of the mitsuke brought settlements of workers, and following the devastating Meireki fire, many more people moved to Yotsuya, which had been spared. Gradually the area became part of the city of Edo.
In 1695, the shogun Tokugawa Tsunayoshi ordered the establishment of a vast kennel. The purpose was to board stray dogs as part of his policy of showing mercy to animals. The facility outside the Yotsuya Gate occupied 20,000 tsubo (66,000 m2; 710,000 sq ft).
In 1894, an extension of the Tachikawa–Shinjuku line of the Kōbu Railway, predecessor of the present-day Chūō Main Line, began to operate. At that time, Yotsuya and Shinanomachi stations opened. This helped transport of raw materials, and soon pencil, tobacco and other industries moved in, bringing rapid development to the area's industry.
Yotsuya has figured prominently in various works of fiction. The kabuki play Yotsuya Kaidan took place there, as did the novel Teisō Mondō by Kan Kikuchi. Yotsuya was also the setting for the Shōtarō Ikenami historical novel Kenkaku Shōbai and the jidaigeki television series based on it.
Many historic temples and graves are in the neighborhood. Among them are Sainen-ji, with the grave of the ninja Hattori Hanzō and a lance once owned by him.