Fermented & preserved ── Fermented seasonings
Koikuchi shoyu
the all-purpose soy sauce used in most Japanese kitchens
The most common soy sauce style, said to account for roughly 80% of national shipments. Made from roughly equal parts soybean and wheat, it carries a reddish color and a pronounced aroma, and serves as the everyday base seasoning nationwide.
Lineage
What it's made of
Its color runs from reddish amber to near-black, and its aroma is pronounced. Umami from soybean layers with the wheat's toasty, faintly sweet note and a clean saltiness, giving it a versatile backbone that works equally well simmered into a dish or poured straight over one. Cold, its saltiness leads; heated, the aroma rounds out and deepens the color, so a teriyaki glaze made from it browns to a glossy sheen. Poured raw over sashimi, it still lets the fish's own flavor show through rather than covering it.
How it's made
Steamed soybeans and roasted wheat, used in roughly equal parts, are seeded with koji mold and cultured for several days. The koji is then mixed with brine into a mash, which ferments and ages in a barrel for six months to a year before being pressed and pasteurized by heat. That near-even soybean-wheat ratio, together with the heat treatment, is what gives it its deep reddish color and strong aroma. The same recipe still varies from brewery to brewery, since each uses its own koji mold strain and aging time.
Why it took this shape
Because soybean and wheat were both reasonably easy to source almost anywhere, brewing wasn't tied to one region. The trade is said to have matured around Edo-period Kanto, spreading nationwide to meet the demand of that huge consumer market. It's said to still account for roughly 80% of national shipments today, with the other four soy sauce styles read as contrasts or offshoots of this baseline — a fairly interchangeable set of ingredients is, in a sense, what let a single 'standard' soy sauce emerge nationwide.
Before you go
- Words about taste and cookingBroth types, spice levels, and noodle firmness — words you're often asked to choose when ordering.
- What to know if you have dietary restrictionsHow allergen labeling works, where fish-based dashi, pork, and alcohol turn up, and phrases for checking with staff.
- How Japanese seasoning tends to tasteWhy Japanese food can taste mild to some visitors, the role dashi and umami play as a flavor base, what soy sauce, miso, mirin, and vinegar each contribute, what "spicy" usually means, and adjusting flavor at the table.
Dishes in the same style
- Choshi shoyuOne of Kanto's leading soy sauce production areas, said to have been founded by merchants from Kishu in the early Edo period. The mild, humid climate — shaped by the meeting of the Kuroshio and Oyashio currents offshore — is said to suit the koji mold and yeast used in brewing, and the town's output helped feed Edo.
- Echigo misoA red, savory miso from Niigata, also called 'ukikoji miso' (floating-koji miso) because its polished whole-grain rice koji appears to float within the paste. Its style is said to vary across Niigata's Joetsu, Chuetsu, Kaetsu, and Sado districts, each shaped by local climate.
Ingredients and dishes from this land
Related lineage
- Usukuchi shoyuA pale-colored soy sauce said to have been devised in the Kanbun era (1660s) in what is now Tatsuno, Hyogo. Soft water from the Ibo River and easy access to local soybeans, wheat, and Ako salt let it develop alongside a Kansai food culture that prizes ingredient color and dashi flavor.
- Shiro shoyuBrewed mainly from wheat with only a small amount of soybean, this soy sauce is nearly amber in color and notably sweet. Hekinan, Aichi is said to be its birthplace, and it is prized for seasoning dishes — such as shiro-dashi — where a pale color matters.
Derived style
- Kyushu amakuchi shoyuA sweetened soy sauce popular across Kyushu, made with added sugar or other sweeteners. Its roots are often traced to sugar arriving early via Edo-era trade with Portuguese and Dutch merchants, and to a local habit of using sweetness to complement very fresh raw fish — it remains the everyday sashimi soy sauce of the region.
- Shodoshima shoyuSoy sauce from Shodoshima in the Seto Inland Sea, whose brewing technique is said to have arrived from Yuasa in Kishu some 400 years ago. Mild climate and easy sea transport once supported some 400 breweries on the small island, and it still accounts for much of Japan's remaining wooden-barrel-aged soy sauce.
- Choshi shoyuOne of Kanto's leading soy sauce production areas, said to have been founded by merchants from Kishu in the early Edo period. The mild, humid climate — shaped by the meeting of the Kuroshio and Oyashio currents offshore — is said to suit the koji mold and yeast used in brewing, and the town's output helped feed Edo.
Uses
- Tamago Kake GohanHot rice with a raw egg cracked over it and seasoned with soy sauce, said to be possible thanks to Japan's thorough egg-safety standards. Widely known by its nickname, TKG.
- Yamagata DashiSummer vegetables and aromatics chopped fine and dressed in soy sauce, eaten raw — a Yamagata staple. It is said to have taken hold especially in the hot, humid Murayama basin as a quick dish for the busy farming season.
- Kamatama UdonNoodles moved straight from the pot to the bowl, unrinsed, and tossed with a raw egg and soy sauce. Mixing it together is said to coat the piping-hot noodles in a silky egg, bringing out both aroma and richness. It is said to have spread as kamaage udon with egg and soy sauce added.
- Abura SobaNo broth is poured at all — noodles are tossed in a soy-and-sesame-oil tare pooled at the bottom of the bowl, said to have started at shops in the Musashino area in the late 1950s, with vinegar and chili oil stirred in partway through.
- Ogikubo RamenA clear amber broth built on bonito and dried-sardine dashi with dark soy sauce tare, said to trace back to soba shops that switched trades and carried their stock-making straight into ramen, lifted by straight, medium-thin noodles.
- TsukemenThick, springy noodles are dipped into a concentrated soy sauce sauce built on sweetness and acidity, said to have started as staff-meal food at a shop in Nakano before being served to customers as an oversized, showy portion.
- Iekei RamenPork bone and chicken carcass simmered long and finished with a dark soy tare and chicken fat, paired with thick, short noodles, spinach, and nori — traced to a shop that opened in 1974 in Yokohama's Shinsugita district and is said to have spread among workers in the surrounding industrial zone.
- Seabura RamenSoy sauce ramen finished with a shower of minced pork back fat that keeps the bowl steaming hot to the last bite, a style said to have taken hold in Tokyo around the turn of the millennium as shops along the Kan-nana ring road competed with each other.
- Odawara-kei RamenA dark, strongly seasoned soy sauce broth paired with flat, curly noodles, often topped with slim, rolled wontons — a bowl said to have taken root at Chinese-style diners in this old castle town.
- Tochio ReidonChinese-style noodles chilled in an iced soy broth, known in Tochio as "reidon" — said to have started when a boy with a sensitive tongue, later the shop's owner, asked for his ramen cold.