Shinjuku is one of the 23 wards of Tokyo, but the name commonly refers just to the large entertainment, business and shopping area around Shinjuku Station.
Handling more than two million passengers each day, Shinjuku Station is Japan’s busiest railway station, served by six railway companies and about a dozen railway and subway lines, including the JR Yamanote Line.
West of the station is Shinjuku’ skyscraper district, home to many of Tokyo’s tallest buildings, including several premier hotels and the Metropolitan Government Office, whose observation decks are open to the public for free.
Northeast of the station lies Kabukicho, Japan’s largest and wildest red light district, while department stores, subterranean malls and electronic shops surround Shinjuku Station on all four sides, including the recently redeveloped south, where the pleasant Southern Terrace is located. Redevelopment there is still ongoing. – japan-guide.com