Anyone who's eaten at a ramen shop will have seen shichimi togarashi, even if they haven't known the name of it.
If it's a humble shop, there will be a branded glass shaker of the commercially made Japanese spice blend on the table; nicer places tend to decant the stuff into a ceramic lidded jar with a tiny spoon. The seven-spice powder contains (according to the jar in my cupboard) chilli pepper, orange peel, black sesame seeds, white sesame seeds, sansho, ginger and seaweed. The use of shichimi is unusual in Japanese cooking; chilli spice is rarely incorporated.
Fancy restaurants that serve subtle dishes (kaiseki, sushi/sashimi or tofu, for example) don't normally have shichimi. It's usually available at more casual izakaya or kushiyaki-ya, ramen and udon shops. Because the spices are ground, the flavours fade quickly; the jar in your cupboard might be "off" even if it hasn't reached its expiration date. A faded colour is the first indication of this. Smell is the second: the sesame seeds give off a rancid odour.
In addition to sprinkling it over bowls of packaged ramen or udon, home cooks should use it in dishes to which they want to add more complexity than pure chilli powders give. I like it in home-made tsukune (chicken meatballs).
Mix hand-minced chicken (preferably thigh meat) with finely chopped chicken cartilage (which gives tsukune its distinctive subtle crunch), finely shredded shiso leaves (or minced spring onion), cornstarch and salt. Shape the mixture into oval meatballs, put them on skewers and grill until fully cooked. While the meatballs are cooking, make a sauce by mixing soy sauce, rice wine, mirin and sugar, and simmering until it becomes thick and glossy. Stir in some shichimi while the sauce is hot, then brush it over the cooked meatballs and grill briefly, until the glaze has caramelised. Serve with a raw egg yolk and more shichimi on the side.