Tofu is another thing that comes in a surprising number of variations. It's not just firm or soft, though those categories do exist. There's "fresh" tofu (obviously not really fresh, since it's wrapped in plastic on a refrigerated shelf), which is very creamy and is sold floating in liquid; there's seared tofu, which is firm and brown on one side; there are various types of fried tofu; and there's my favorite - silky, smooth, plain blocks in individual, bad for the earth, packaging. The brand at the far lower right is among the best - silken perfection.
Of course there are all kinds of fish (meat, too) in the supermarket. Fish comes pre-sliced for sashimi, in larger cuts for sauteeing or baking, and in the form of a whole fish (not necessarily cleaned - an unhappy surprise for the American purchaser). There's also a selection of dried fish, shown above. I've seen on TV how they're processed, by being split in half, salted, skewered, and hung in a cage overnight to dry out. But I have no idea what you're supposed to do with them in your kitchen. I think you grill them. But I haven't ever tried it, and probably never will. Tofu is just much easier.
Speaking of easy, most supermarkets also have a deli section with pre-cooked food all ready to be taken home and re-heated. Things on a stick are always popular - here I think we're looking at yaki-tori, grilled chicken, front and center. There are some fried vegetables and fish in the back at left, and in the foreground at right is some braised eel. When I was moving into my apartment and didn't have any pots or plates yet, I ate supermarket food for several days, and it was pretty good - not to mention a great way to feel like one of the locals.