Convenience stores are a great place to find a nice snack, some basic necessities, and even a hot meal. When Americans think of convenience stores, they don't often picture buying healthy or particularly good food, but in Japan, conbini can be a great spot for a quick lunch, or hit them up at the end of the day for discount hot foods.
Essentials:
100 Yen Stores- Very popular budget stores similar to "dollar stores" in the US. At 100 yen stores like Don Quixote, Daiso, or Can*Do sell almost everything: housewares, stationery, toys, and everything else you'd want for your room abroad on a student budget.
Supermarkets - There are many different supermarket chains in Japan. Some of the most popular ones are: Izumiya, Tobu Store, Inageya, Daiei, Maruetsu, Seiyu, Ito-Yokado.