When people say "soy sauce," it usually means koikuchi shoyu.
Darker color (between tamari and usukuchi) and very aromatic.
(Marudaizu Shoyu by Yamasa; 940 mg sodium/tablespoon)
Paler color and used for dishes where a less brown tone is desired.
Has a higher sodium content than koikuchi, and add a sharp bite. Do not overuse.
(Usukuchi Light Color Soy Sauce by Kikkoman; 1150 mg sodium/tablespoon)
Genen shoyu reduced-sodium koikuchi soy sauce
This is the 50% reduced-sodium soy sauce I use. By simply replacing the regular koikuchi soy sauce shown above, this soy sauce (Tokusen Marudaizu Genen Milder Soy Sauce by Kikkoman; 470 mg sodium/tablespoon) can reduce overall sodium content of your dishes. And by incorporating other techniques, you can further lower sodium in final dishes.
Thick, rich and sweet.
Similar to thick Chinese soy sauce.
Contains no wheat.
(Last updated: February 15, 2015)