Tosa Shuzō is a Japanese sake brewery founded in 1877 in Tosa, Kōchi Prefecture, on the island of Shikoku. It is best known for its Keigetsu brand, whose identity is rooted in the mountainous Tosa-Reihoku region, local rice, and pure water.

The brewery is located near Lake Sameura and the headwaters of the Yoshino River, in an environment that provides high-quality soft water for sake brewing. It places particular emphasis on rice grown in local terraced fields and traditional brewing methods such as kimoto and yamahai.

Its range includes junmai daiginjō sake, traditional yamahai releases, seasonal unpasteurized sake, and sparkling products. Through different rice varieties, yeast strains, and brewing methods, the brewery creates profiles ranging from fresh and intensely fruity to fuller-bodied, more complex sake.