Shinjuku 新宿 must be one of my favourite wards in Tokyo. While it is a business district, it is also home to considerable dining, entertainment and shopping options. http://danielfooddiary.com/2017/04/23/shinjuku/
There are TOO MANY food choices to list down here. Omoide Yokocho (also nicknamed the Piss Alley) is literally lined with yakitori, oden and soba shops. Or you can just go to Takashimaya and Isetan basement, especially during closing times to get some discounted food buys.
10 Must Eats At Shinjuku Tokyo 新宿 - Favourite Restaurants & Cafes In Shinjuku