If you are referring to bentos purchased at convenience stores in Japan, they are generally divided into two types: hot and cold. If it is hot food, such as various bento boxes with rice, the cashier at most convenience stores will ask if it needs to be heated when checking out. A few stores will use the microwave oven next to them to heat it after checkout.

The types of cold lunch boxes include various salads (some with cold noodles and salad), diced fruits, rice balls (hand-held rice balls, triangular rice balls and the like that are individually packaged), sandwiches, comprehensive sushi bento boxes, various Side dishes, side dishes, etc. (the above are usually individually packaged and sold) are generally eaten directly without heating. If you want to eat the rice balls hot, you can also ask the cashier to microwave them when you check out.