Shōyu (Soy Sauce)
Shōyu, or soy sauce, is perhaps the most well known of Japanese condiments. It's a dark sauce made from fermented boiled soybeans and roasted wheat which has a salty but pleasant, savory taste. You will find it not only in traditional Japanese restaurants but also in most any restaurant in Japan.
It's the most essential condiment for Japanese cuisine such as sashimi and sushi; at traditional sushi restaurants, soy sauce is also called "murasaki".
Salt is a condiment used in every country, but here in Japan you might run across some interesting different types of salt, such as rock salt or even matcha salt (green tea salt). In fact, tempura (battered and deep fried seafood and vegetables) is sometimes eaten with salt instead of tempura sauce (which is soy sauce based) in order to bring out the different flavors of the ingredients.
If you take a closer look at the salt shakers, you might see some larger white grains inside - it's rice, placed in there to absorb moisture and keep the salt dry.
Pepper is also used in most of the countries in the world and Japan is no exception. There are two types of pepper commonly found in Japan: black pepper and white pepper. White pepper is more commonly found at Chinese restaurants, and because it looks quite similar to salt, it's a good idea to double-check before adding it to your meal. Black pepper could be in either a pepper mill or in a shaker.
Shichimi (Seven Spice Blend) & Ichimi (Chili Pepper)
You will find red flakes like in the picture above at soba or udon noodle restaurants. There are two types, one is called ichimi which is ground dried red chili peppers and the other is shichimi which is ichimi with six other spices added to it. Even if you're a spicy food fan, be really careful adding this to your dishes as a little goes a long way.
Rāyu (Chili Oil)
You will find this vivid red oil in Chinese restaurants and at rāmen shops. It's made from chili peppers and it is really potent when added to dishes, even if you only add a small amount. Though it's mostly used to make sauce for gyōza as mentioned above, if you're a spicy food fan, why not add it to other dishes too?
Beni Shōga (Pickled Ginger)
Beni shōga is found mainly at gyūdon-ya (beef and rice bowl restaurants) and Hakata rāmen restaurants. It is ginger pickled in plum vinegar and colored with shokubeni. It tastes sour, sweet, salty and spicy all at the same time. Its vivid red-pink hue gives dishes a pop of color and is said to boost your appetite.
Wasabi is a green paste condiment prepared at traditional Japanese restaurants. It's eaten with sushi and sashimi, as well as other raw fish dishes. You may experience a burning sensation inside the nose or even pain in your head if you eat too much at once, but this doesn't last very long. This is a completely unique Japanese condiment, so you should definitely try it when here.