When Godzilla first landed in Japan in 1954, Tokyo was his first place to visit. It's not surprising to see Godzilla be part of the city skyline in tribute to this cinema great.
Godzilla is located on top of the Shinjuku Toho Building. Here is a link to a web page with information on it.
Toho Cinemas is the Japanese film/cinema company responsible for the creation and theatrical distribution of Godzilla's films.
On top of the building is a cafe/restaurant. Seeing Godzilla is free but like anything "free" you must enter the cafe, place an order for coffee or a light snack, to be able to walk out on the terrace (through the cafe) and be terrorized by one of cinema's greatest creatures conceived. It's worth the vist.