Common soy sauce is the most widely used of the soy sauce varieties nationwide. The main manufacturing methods are:

1. honjozo (regular fermenting method)

2. kongo jozo (semi-fermenting method)

3. kongo (mixing method)

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1. Honjozo

Honjozo is the traditional way of making soy sauce (approximately 80% of production). Steamed soybeans (defatted soybeans) and toasted wheat are mixed in roughly equal proportions and koji mould spores are added to create koji. The koji is placed in a tank with brine to create moromi, which is left to rest for around six to eight months, with repeated stirring. Breakdown and fermentation proceed through the action of koji mould, natural yeast, lactobacillus and other microorganisms, and further maturation produces the distinctive colour, flavour, and fragrance of soy sauce.

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2. Kongo Jozo

Another method is kongo jozo, in which amino acid fluid and other ingredients are used in brewing to produce a unique savoury taste.

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3. Kongo

Using Kongo as a production method means amino acids etc. are used to shorten the manufacturing time. In these ways, soy sauce producers add new technological ideas while maintaining old traditions, to make products that are always of stable quality.