[ Yotsuya] Originally, a bleak part of the Musashino Plains, the area where Yotsuya 4-chome Intersection is today used to be a single road with nothing but deep thickets and valleys on either side. Then, four teahouses where travelers could rest were established. It is said that the name Yotsuya as we know it today with the characters for “Four Valleys” evolved from the name Yotsuya with the characters for “Four Shops.”
[Ushigome] The word “kome” means “to be crowded,” and it is said that this name came about because long ago, there were many cows put out to graze in this area. Lord Ogo of the state of Kozuke (what is now Gunma Prefecture) came to live in this area, and called himself “Ushigome” about 450 years ago in 1555. Lord Ushigome was affiliated with Lord Hojo of Odawara, and owned the land from Ushigome to Hibiya, and the castle was located on the plateau of the Fukuromachi area. The grave of Lord Ushigome is still located in Sosanji Temple (1 Bentencho).
[Yodobashi] It is said that the name of the bridge crossing over the Sumida-gawa River that flowed between Naruko-Mura Village and Nakamura Village evolved from being called Yodo- (Extra) or Yodo- (Four Places) Bashi (Bridge). It is also said that when the third ‘Shogun,’ Iemitsu Tokugawa was resting by the bridge during the Kan’ei Period, he thought that the flow of the river seemed to be almost stagnant (“yodomu”), and decided to call the bridge Yodobashi. There is also a story that the eighth ‘Shogun,’ Yoshimune named the bridge Yodobashi during the Kyoho Period because the scenery reminded him of Yodo in the state of Yamashiro (what is now Kyoto). There are also various other stories, all of which seem to explain how the name of the area evolved from the name of the bridge.
The area has many movie theaters, and because it is located near Shinjuku Station, Seibu Shinjuku Station, and several other major railway and subway stations, tickets to its top attractions can be scarce.
Kagurazaka is also widely regarded as an important center of Japanese cuisine within the Kanto region. Several old and famous "ryotei" are to be found in the winding back streets, often accessible only by foot. These ryotei provide expensive "kaiseki" cuisine, which is generally regarded as the pinnacle of Japanese food. Ryotei also allow diners to invite geisha to provide entertainment during the course of the evening.
The Kagurazaka Awa Odori (Japanese: 阿波踊り) festival is held the fourth Friday and Saturday each July.
At the top end of Kagurazaka is Akagi Shrine (Akagi Jinja/赤城神社).
Nishi-Shinjuku was Tokyo's first major foray into building skyscrapers with the first appearing in the 1970s with Keio Plaza Inter-Continental. Kenzo Tange's Tokyo Metropolitan Government Building being the current latest. Tower I was also the tallest building in Japan at this time.
Progress continues in Nishi-Shinjuku and in West Shinjuku which is heading away from the city center and has the site of the proposed Nishi-Shinjuku 3-Chōme Redevelopment with plans for what will be three of the 4four tallest buildings in Japan.
Surrounding Shinjuku Station are department stores, specialist electronic and camera shops, cinemas, restaurants and bars. Many international hotels are located here.
Shinjuku has the highest numbers of registered foreign nationals of any community in Tokyo. As of October 1, 2005, 29,353 non-Japanese with 107 different nationalities were registered in Shinjuku.
Within close walking distance from three train stations (Shinjuku San-chōme Station, Shinjuku Goenmae Station, and Japan's busiest train station, Shinjuku Station), the Shinjuku Ni-chōme neighborhood provides a specialized blend of bars, restaurants, cafes, saunas, love hotels, gay pride boutiques, cruising boxes (hattenba), host clubs, nightclubs, massage parlors, parks, and gay book and video stores. In fact within the five blocks centering on street Naka-Dori between the BYGS building at the Shinjuku San-chōme Station and the small Shinjuku park three blocks to the east, an estimated 200-300 gay bars and nightclubs provide entertainment.
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.
In 1634, during the Edo period, as the outer moat of the Edo Castle was built, a number of temples and shrines moved to the Yotsuya area on the western edge of Shinjuku. In 1698, Naitō Shinjuku had developed as a new (shin) station (shuku or juku) on the Kōshū Kaidō, one of the major highways of that era. Naitō was a daimyo whose mansion stood in the area; his land is now a public park, the Shinjuku Gyoen.
Shinjuku began to develop into its current form after the Great Kantō earthquake in 1923, since the seismically stable area largely escaped the devastation. Consequently, West Shinjuku is one of the few areas in Tokyo with many skyscrapers.
The Tokyo air raids from May to August 1945 destroyed almost 90% of the buildings in the area in and around Shinjuku Station.  The pre-war form of Shinjuku, and the rest of Tokyo, for that matter, was retained after the war because the roads and rails, damaged as they were, remained, and these formed the heart of the Shinjuku in the post-war construction. Only in Kabuki-cho was a grand reconstruction plan put into action. (Ichikawa, 2003)
In 1991, the Tokyo Metropolitan Government moved from the Marunouchi district of Chiyoda to the current building in Shinjuku. (The Tokyo International Forum stands on the site vacated by the government.)
It was after Tokyo Metropolitan transferred, that Shinjuku gradually transfigured to take on its present shape and color.
The name Shinjuku is derived from 'Naito Shinjuku,' from the 11th year of Edo's Genroku Period (1698), when Shinjuku was newly (shin) established as a town of inns ('shuku' becomes 'juku' in Shinjuku) that cropped up around Koshu Highway as it ran from the then Yotsuya Okido. Shinjuku was an important area from Edo's prosperous inn districts along with Shinagawa, Senju, and Itabashi.
The 'naito' of 'Naito Shinjuku,' comes from Takato Hanshu Naito, the name of an inn compound erected in this Shinjuku of Edo.
Later, in the wake of this gigantic compound, was the development of Shinjuku Gyoen National Garden. Many a historic spot and item of cultural importance are directly connected to Naito Shinjuku.