What I like about the uk mini stores is that you have healthy options and I mean balanced foods with veg and clear color coded signage of it's nutrition like salt, saturated fat, calories, 5 a day etc. In Japan kombinis have no fresh veg, any pre made food has nothing fresh or green in it (or very very little) and it's generally more difficult to find fresh things in the big cities that I've been in Japan. Fruit? Same story but a lot more expensive although much tastier but sometimes having an option is better even if it's underpar.