Masumi Sake: The Nagano Brewery Behind Japan’s No. 7 Yeast

Most sake brands are known for a taste, a rice, or a famous bottle. Masumi is known for something you cannot see: a yeast. In 1946, researchers isolated a yeast from sake fermenting at this Nagano brewery. The strain was later distributed to breweries across Japan as Brewing Association Yeast No. 7. Masumi therefore offers a clear entry point into the history of modern sake brewing. This guide covers where the brand comes from, how No. 7 works in plain language, which bottles to try first, and what to expect in the glass. Quick Facts: Masumi SakeJapanese name真澄 (Masumi)BreweryMiyasaka Brewing Company (宮坂醸造)LocationSuwa City, Nagano Prefecture, central Japan; a second brewery in FujimiFounded1662, according to the breweryKnown forThe brewery where Brewing Association Yeast No. 7 was isolated in 1946Yeast todayProprietary strains related to No. 7, the focus since 2019RiceAbout 80% from Nagano and 20% from Hyogo (brewery figures)Good first bottlesKURO or SHIRO for everyday drinking; Nanago for the No. 7 story TOCWhat Is Masumi Sake? Masumi (真澄) is a sake brand, not a style of sake. Miyasaka Brewing Company makes it in Suwa, a lakeside city in the mountains of Nagano Prefecture. The br...