What's a "yelp-like service"?
Don't worry about eating. Go to that link, or even buy the related book What's What in Japanese Restaurants. Shinjuku is a thriving hub of activity, so restaurants will abound, and menus have tons of pictures. Store fronts of many restaurants will show plastic models of the more popular dishes, too, so you can get an idea of what they serve before you go in.
When in doubt, hit Royal Host or Victoria Station restaurants. Lots of western variety foods there.