Japanese Shoyu Soy Sauce Regional Varieties Koikuchi Usukuchi Tamari
Japan — Chiba (Noda and Choshi), Hyogo (Tatsuno), Aichi (Hekinan) as major shoyu production centres
Shoyu (soy sauce) is not a single product in Japan but a diverse category of fermented seasonings with five distinct classifications, each with dramatically different characteristics, regional associations, and culinary applications. The five types: Koikuchi (dark soy sauce, 80% of Japanese production) — standard balanced soy sauce, dark colour, full aroma and flavour; the default shoyu for most applications; produced primarily in Chiba (Kikkoman's home). Usukuchi (light colour soy sauce, 12–14%) — lighter colour but higher salt content than koikuchi; developed in Hyogo (Tatsuno) for Kyoto and Kansai cuisine where light colour is valued to preserve the natural colours of ingredients; usukuchi is saltier than koikuchi but the flavour is lighter and less aromatic. Tamari (4%) — made primarily from soybeans with little or no wheat; very dark, thick, intensely savoury; the original soy sauce tradition; preferred for dipping sashimi and making teriyaki-style glazes. Shiro shoyu (white soy sauce, 2%) — light amber colour, made from predominantly wheat with minimal soybean; produced primarily in Hekinan, Aichi; used to season dishes where neither colour nor strong aroma is wanted. Saishikomi (twice-brewed soy sauce, <1%) — fermented a second time in existing soy sauce rather than brine; extremely dark, sweet, complex; used for sashimi dipping and as finishing sauce.