Marunaka brewed soy sauce (koikuchi, dark soy sauce): every ingredient on the label
丸中醤油 丸中醸造醤油（こいくちしょうゆ）
Only three ingredients: soybeans, wheat and salt. A koikuchi (dark) soy sauce from a brewery in Koto, Shiga, aged in cedar barrels, with three years of aging as the basic standard.
Checking the ingredient list against the additives you flagged.
Choose additives to flag →The label on the back
| 名称Name | こいくちしょうゆ（本醸造） |
|---|---|
| 原材料名Ingredients | 、、 |
| 内容量Net contents | 720ml |
| 賞味期限Best before | 下部に記載 |
| 保存方法Storage | 直射日光を避け、常温で保存 |
| 製造者Manufacturer | 丸中醤油株式会社 滋賀県愛知郡愛荘町東出二二九 |
| Energy エネルギー | 12.3kcal |
| Protein たんぱく質 | 1.3g |
| Fat 脂質 | 0g |
| Carbohydrate 炭水化物 | 1.7g |
| Salt equivalent 食塩相当量 | 2.4g |
Copied from the package as of the date checked. The label is shown in Japanese as printed; tap an ingredient to see its English name and role. The links in the table below lead to our Ingredients A–Z and food additive database. Wheat and soybeans are allergens, but because they are written in the ingredient list itself, there is no “（一部に〜を含む）” (contains ... in part) statement.
Ingredients, one by one
| On the label | Type | Role | Notes |
|---|---|---|---|
| 大豆（国産、遺伝子組換えでない）soybeans (domestic, non-GMO) | Ingredient | Main ingredient, source of umami | Origin labeling of ingredients is required only for the ingredient that is largest by weight. That is why only the soybeans have an origin written. “遺伝子組換えでない” (non-GMO) is not required for soy sauce; it is a voluntary label by the maker. |
| 小麦wheat | Ingredient | Aroma and sweetness | Roasted and crushed wheat gives soy sauce its characteristic aroma. The label has no origin for the wheat, but the official shop explains that domestic wheat is used. |
| 食塩salt | Ingredient | Suppresses unwanted microbes during fermentation | Koji is mixed into salt water and aged as moromi (fermenting mash). The official shop describes the salt as “天日塩” (sun-dried salt). |
Not found in the ingredient list
This is not the maker's “not used” claim. These are things often seen in similar products that we checked are not written in this product's ingredient list. Additives carried over from ingredients may not be declared, so this does not mean they are absent (about additives not written on labels).
Next to a typical product
大豆（国産、遺伝子組換えでない）、小麦、食塩
脱脂加工大豆、小麦、食塩、大豆、アルコール／調味料（アミノ酸等）、甘味料（甘草、ステビア）、カラメル色素
This is an example often seen in low-priced products. Food additives are shown in red. Alcohol is added to prevent mold after opening, and is treated as an ingredient on the label. “脱脂加工大豆” (defatted processed soybeans) are soybeans after the oil has been pressed out.
Good points and concerns
+Good points
- 3 ingredients, all foods. No food additives
- Aged in cedar barrels used for over a hundred years, with three years of aging as the basic standard (from the official site)
- A long best-before period of 2 years (from the official shop)
−Concerns
- ¥1,788 for 720 ml (about ¥248 per 100 ml). More expensive than a typical koikuchi soy sauce at a supermarket
- Free shipping at the official shop starts from ¥10,800
- It is advised to close the cap right after opening and store in a cool, dark place
Related articles
Sources
- Marunaka brewed soy sauce, 720 ml | Marunaka Shoyu official shopping site
- Marunaka Shoyu official shopping site (explanation of the brewing method)
- Label on the back of the package (checked 2026-09-27)
This page is a translation of our Japanese page; if they differ, the Japanese page is the reference.
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