In Tokyo it is very easy to find simple, tasty food for low cost.
As a visitor you are naturally going to feel drawn to what you are used to and as in other major cities, familiarity is often accompanied by higher prices. For those who are less fearful of new places and cultures, there are an amazing array of inexpensive restaurants, bars and cafes.
Communication will always be a problem, as small restaurant owners rarely speak fluent English. Many restaurants can still function admirably when faced with a language barrier.
The restaurants to look for are those with pictures and examples of their signature dishes on the outside of their restaurants. Some have 3D versions, some have dozens of 10x8 images. If you see these restaurants, take time to study the cuisine and find one that looks appealing. Simply walk in and ask for a table to suit your party (a simple process of how many seats you require). Appoint one member of your party to communicate with the waiting staff. All this party member has to do is take the waiter to the pictures and point slowly to each meal that you require ... simple and usually welcomed by the waiting staff, who must struggle with less organised patrons.
The meal above cost just £8 for two meals and two teas. It was filling and tasty. Be aware that these restaurants are often a bit smoky, so there is always that to consider.