Kikkoman built its original factory in the 17th century in Noda, a town about 35 miles from Tokyo. Today, a small, lovely building constructed in 1939 produces shoyu for the royal family in a traditional style similar to that of Denkichi Matsuno. The inestimably larger, newer plant is automated, filled with stainless-steel and aluminum machinery and vats, and looks much like a brewery (which, in fact, it is). Kikkoman also has two plants in the United States, two more in Japan, and one each in Singapore, Taiwan, China, and the Netherlands.
Despite its size, Kikkoman is proud of its "natural" soy sauce, and although—to continue the comparison to beer making—it runs Budweiser-sized and -style plants, the quality of its mass-produced shoyu is high (it even makes an organic version). Usually, it completes the process in six months, at some cost to complexity, but the basic ingredients remain soy, wheat, yeast, and salt. Contrast this to the cheap black soy sauce made throughout Asia that sells for around a dollar a bottle. It can only be called "soy sauce" because its base of hydrolyzed vegetable protein is made from soy, which is treated with hydrochloric acid and then combined with salt and caramel; production takes three days.
Back in Tokyo, I make the requisite pilgrimage to Tsukiji, the busy central Tokyo fish market, officially named Tokyo Chuo Oroshiuri Ichiba, where the early-morning tuna auctions are so famous they attract tourists, even at 5 a.m. To me, the varied and beautiful seafood is less important than the shops surrounding the market, where people sell utensils, shave bonito to order, and offer fresh matsutake, the phallus-shaped wild mushroom that is so popular here.
In Tsukiji Market Building No. 6 (addresses in Tokyo are a real adventure) is Daiwa, an ordinary-looking sushi bar, but one where the reverence for fish, rice, and shoyu—and beer—is palpable. I eat a superb breakfast of rich toro (tuna), lightly pickled mackerel, yellowtail, abalone, flounder, ark shell (a kind of huge mollusk), blood clam, and octopus. The rice is slightly warm—a sure sign, in Tokyo at least, of a high-quality place—and every piece of fish is glazed with a light sauce of shoyu and mirin (sweet rice wine) just before it's served. This mixture, on which the best sushi chefs pride themselves, is added to daily, often making the base years and years old. My dining companion whispered, "If there's ever a fire, the shoyu base is the first thing the chef will grab."
That night, after a super-hot soak in a neighborhood bathhouse, I hit a small restaurant named Tatsukichi in a nearby Yokohama suburb called Hiyoshi. Here, freshly made soba (buckwheat noodles) is served with soba tsuyu, a dipping sauce of dashi, mirin, and shoyu. The tempura moriawase—an informal dish of onions, vegetables, and shrimp, all stuck together from frying—is served, of course, with soy sauce. The meal concludes when my host asks for soba yu, the water the noodles were cooked in: we mix it with the leftover soba tsuyu, spike it with chile and shoyu, and drink it like tea, a splendid tradition.
When I return to New York, I reflect on this evening and all the other uses I had seen for shoyu. I recall a discussion I had with one of the hosts of a multi-course restaurant meal in which nearly every single plate—tofu, meat, fish, vegetables, egg dishes, and condiments—contained shoyu in one form or another. I'd remarked on this and wondered whether it was common in Japanese homes as well as in restaurants. "Of course," she said. "Shoyu makes everything taste good. That's why we like it on hamburgers."
MARK BITTMAN is a food writer and columnist for the New York Times.