Horaiya, Koji Soy Sauce, 340ml
Dark soy taken a step further. Horaiya blend finished soy sauce with their own rice koji and mature it again, for a rounder, sweeter, thicker soy you dip rather than cook with.
Why Chefs Choose This
- Refermented with rice koji: finished soy is blended with the brewery's own koji and matured again, which builds the rounder, sweeter depth.
- A finishing soy, not a cooking one: thick and mellow enough to dip sashimi, tofu and sushi straight from the bottle.
- Koji-makers since 1906: Horaiya Honten in Fukushima have grown koji for over a century, and it is the koji that defines this soy.
- You can see the koji: grains of rice koji settle in the bottle, the visible mark of how it is made. Give it a shake.
How to Use
- Sashimi and sushi: a dipping soy with body and a gentle sweetness behind the salt.
- Hiyayakko: spoon it straight over chilled tofu, the classic Japanese pairing.
- Over rice and egg: a few drops on tamago kake gohan or steamed rice.
- Off-piste: use it as a finishing soy on grilled meat, roast vegetables or in a dressing where you want sweetness and depth.
Koji is written 麹, the cultured rice (Aspergillus oryzae) that sits behind miso, sake and soy sauce. Horaiya Honten, founded in 1906 in Koriyama, Fukushima, are koji specialists first and foremost. For this soy they take a dark koikuchi soy sauce, blend in their own rice koji and let it mature, so the koji works its sweetness and umami into the finished sauce. That is why it pours thicker than ordinary soy and carries a mellow, rounded edge rather than a sharp salty hit. The whole rice grains you can see in the bottle are the koji itself, left in rather than filtered out.
What does koji soy sauce taste like?
Rounder and sweeter than a standard dark soy, with the salt sitting further back. The koji brings a mellow, almost malty sweetness and a thicker body, so it coats food rather than running straight off. There is still the savoury depth you expect from a good shoyu, but it is softer and less sharp, closer to a finishing sauce than a cooking one. A drop on sashimi or chilled tofu tells you what it is for: it adds flavour and a little richness without the bite of ordinary soy. Shake the bottle first to lift the koji through.
| Type | Koji Shoyu (麹醤油, dark soy sauce with added rice koji) |
| Brand | Horaiya Honten, founded 1906, Koriyama, Fukushima |
| Key Feature | Dark soy blended with the brewery's own rice koji and matured; rounder, sweeter, thicker; visible koji grains |
| Origin | Koriyama, Fukushima Prefecture, Japan |
| Volume / Format | 340ml bottle |
| Best Used As | A finishing and dipping soy for sashimi, tofu, sushi and rice |
What is koji soy sauce?
It is a dark soy sauce that has had rice koji blended into it and been left to mature. Koji is the cultured rice used to make miso, sake and soy in the first place. Adding more of it to a finished soy, as Horaiya do here, draws out extra sweetness, umami and body. The result pours thicker than normal soy and tastes rounder and less sharp, with grains of the koji visible in the bottle.
How is it different from normal soy sauce?
Standard dark soy is sharp, salty and thin, made to cook with. This one has been refermented with rice koji, so it is sweeter, thicker and more mellow, with the salt further back. That makes it a finishing soy rather than a cooking one: you reach for it to dip sashimi or spoon over tofu, where its body and sweetness do the work, rather than pouring it into a hot pan.
How should I store it after opening?
Keep it in the fridge once opened and shake before each use, as the koji naturally settles to the bottom. A little sediment is normal and is simply the rice koji left in the bottle. Stored cold and closed, it holds its flavour well, though like any soy it is best used while fresh rather than left for years.
SKU : S0306