When you buy a bottle of soy sauce for Japanese food, make sure to buy Japanese soy sauce. Similar sauces are widely used in Asia, but depending on the country, the flavor and texture are quite different in each country. For instance, I have 3 different bottles of soy sauce in my refrigerator, 1 for Japanese food, and 2 others for Thai food.
Kikkoman is a standard Japanese brand and readily available in many American grocery stores. You can also find reduced sodium, no GMO, organic. Many other premium soy sauces are sold at health food stores and Japanese grocery stores. Some are imported from Japan, and others are made in the U.S.
You also might have seen a type called tamari, at health food stores. Tamari has thicker and richer flavor than regular soy sauce. Unlike soy sauce, wheat is not used to brew tamari. Tamari is great to dip sashimi or sushi.
Soy sauce can turn darker and flavor also deteriorates by time. After opening, always store the bottle in a refrigerator, and try to finish it within 6 months or so. If you don’t use it often, buy a small bottle.
If you want to order online, here are some of the links;