Shinjuku was an ENORMOUS city with an equally as colossal of a station to match. Lots of great watch store options here. While the shops here aren't as concentrated as Nakano, the variety and prices were really great. Plus you get to see all sorts of people - locals and tourists - doing various things in between the destinations. Definitely visit Okura, WatchNian, and BEST Shinjuku Flagship store while you're there!