Convenient stores are where locals can be seen picking up a snack or meal, along with other necessities, in the nick of time. The sister and I have visited both Family Mart and 7-11 for supper. Priced about ¥100-¥200 cheaper as opposed to eating at a sit in restaurant, portion size is reasonable and taste is agreeable.
Cashiers usually offer to microwave your food for you at no charge. Choose from bento boxes filled with rice, chicken and a bit of pickles to takeaway containers of noodles or for a lighter meal, perhaps a savoury bun or an onigiri (rice ball with filling). For completion, milder content alcoholic beverages are readily available or for tourists like me, a refrigerated green tea drink will do the trick.