Yamasa Soy Sauce Factory — 400 Years of Fermentation

**Barrel-aged premium soy sauce:** The factory shop sells limited-edition soy sauce aged in 100-year-old cedar barrels (kioke) for 3+ years — unavailable in regular stores. The 720ml bottle (¥1,800) is noticeably more complex than standard soy sauce, with caramel and umami depth. Perfect for sashimi and sushi dipping. **Tasting comparison:** The tasting area offers side-by-side comparison of koikuchi (dark soy sauce, 80% of Japanese production), usukuchi (light, saltier), tamari (thicker, wheat-free), and shiro (white soy sauce, almost clear). The differences in aroma, viscosity, and salinity are revelatory. **Historical warehouse:** The Edo-period warehouse retains original clay walls and wooden beams darkened by 300+ years of soy sauce fermentation. The walls host koji bacteria colonies passed down through generations — the building itself is part of the flavor profile. **Combine with Choshi Fish Market:** Choshi Port (10 min by car) is Japan's top fish landing port by volume. The morning market (6:00–9:00) sells sashimi-grade tuna, sardines, and mackerel direct from boats. Buy sashimi + fresh wasabi + Yamasa soy sauce for a DIY premium experience.