Shinjuku (新宿区 Shinjuku-ku, "New Lodge") is a special ward in Tokyo, Japan. It is a major commercial and administrative centre, housing the busiest railway station in the world (Shinjuku Station) and the Tokyo Metropolitan Government Building, the administration centre for the government of Tokyo. As of 2015, the ward has an estimated population of 337,556 and a population density of 18,517 people per km². The total area is 18.23 km².