Japanese convenience store food is surprisingly fresh and reasonably priced. In particular, I am a big fan of the sandwiches, which come with many fillings, like tuna or egg salad, katsu (fried pork cutlets), or as seen above, ham and cheese with lots of fresh iceberg lettuce. The sandwiches are about 250 JPY. When I am craving vegetables I get this sandwich.
These are actually from two different shops. 7-11 on the left and Family Mart on the right. The 7-11 was better as it was made with mayonnaise and the lettuce was crispier. I think the Family Mart was made with butter.
A chef friend of mine is addicted to the egg salad sandwiches, which are pretty amazing.
The sandwiches also make for a quick breakfast if you are on the run.
convenience store = konbini
Food Sake Tokyo 
I have to agree — the konbini sandwiches are an incredible deal. I opt for the extra lettuce with ham and cheese at Natural Lawson, which look very much like the sandwich from 7-11 as shown, and comes complete with mayo. Those sandwiches are a great late night snack!
I need to try Natural Lawson. I don’t pass any on a regular basis, but great tip, arigato!