Mito Natto: Ibaraki's Fermented Soybean Tradition

Mito, Ibaraki's capital, has been linked with natto since at least the Meiji era, when small, uniform soybeans grown on the surrounding Kanto plain proved ideal for fermentation. Local lore ties the connection back to samurai-era travelers who carried cooked soybeans wrapped in rice straw, letting natural bacteria on the straw ferment them into natto en route. Whatever the exact origin, travelers passing through Mito Station have bought natto as a souvenir for well over a century, and the city still markets itself, informally, as Japan's natto capital.

Ibaraki natto is traditionally the small-bean (kotsubu) or ultra-fine (hikiwari) kind, valued for a stickier, more uniform texture than large-bean styles sold elsewhere. Locals stir it briskly until the strands turn pale and foamy, add the packaged soy-based tare and a dab of karashi mustard, then spoon it over hot rice, sometimes with raw egg and scallion. Straw-wrapped natto (wara-zutsumi), sold as a novelty souvenir, ferments less evenly and smells stronger than standard packs — worth trying once, but confirm current shop availability before planning a special trip.