Rice Sources
Rice
Here is a list of known rice vendors. Whether or not the rice is specialized for making sake (ex.- Yamada Nishiki) or food rice that can be used for sake making, the rice still must be polished much more than food rice. This calls for a specialized mill. And that greatly limits the number of vendors outside of Japan.

Minnesota Rice and Milling
Offers a variety of rice types for sake brewing including Yamada Nishiki and Calrose.

Valley Select
“For decades, California rice varieties have been used by Japanese sake breweries in the United States to produce high quality sake brewed in the US for the US and export markets.
In 2012, Valley Select noticed a need for more high quality sake rice to serve sake breweries here in the US. Valley Select invested in state of the art, Japanese equipment, designed specifically to mill rice for the highest quality, Dai Ginjo sake.”
Koji Sources
Koji
To convert sake rice into sugar that can be fermented, koji-kin is delicately distributed over steamed sake rice in a very hot, humid room. Over a period of 48 to 72 hours, the mold is carefully cultivated to grow evenly onto the sake rice. When the “moldy rice” is ready to be incorporated with the other elements of the sake, there is a noticeable, sweet chestnut-like aroma coming from the rice. To the naked eye, each grain of rice appears to be coated with a white frost.
This cultivation of koji (once koji-kin is fully grown onto sake rice, it is simply called “koji”) is often considered the most important part of the sake brewing process. Although the method of koji-making varies greatly from one brewery to another, in each brewery the koji muro (room for making koji) is the most sacred and revered part of the brewery.

Akita Konno (Japan)
Since establishment of our company, we have had a lot of industry-university and industry-academic-government joint research and development. In those, there are white Koji fungi as stated above, non-dark and non-black pigment Koji fungi , leucine acid high productive Koji fungi (received Tohoku Invention Recognition Invention Exhortation award 1990 fiscal year), anti-fungi material “Asperatine”. The Institute of Biotechnology Applied to Eumycetes was established by investment of the Biologic Specific Industry Investigation Promoting Government Organization 1994 and we are making rapid progress as general microbe starter maker.

Higuchi Moyashi (Japan)
“Principal Clients: Over 85% of Japanese sake, miso and soy sauce manufacturers. Most leading shochu manufacturers.
Business: Koji starters of all kinds used in the production of sake, miso, soy sauce shochu and mirin. Marketing of enzyme preparations for brewing, including products from Amano Enzyme Co. Ltd., Daiwa Fine Chemicals Co. Ltd. and HBI Co. Ltd.”

Tokushima Seikiku (Japan)
“Tokushimaseikiku is producing ‘Dry Koji’ with their patented dry system that enables the product to maintain its quality for the long term even though usual koji can’t do it. You can use not only for the fermented food such as Alcohol Beverage, Miso and Mirin but also for bakery dough instead of yeast food.”
Yeast Sources
Yeast
Over the past 100 or so years, many types of yeast have been isolated and developed for sake brewing. They can range from low aroma traditional yeast to the more modern strains that give fruity “ginjo” aromas. Below is a list of know providers.

Akita Konno
“Since establishment of our company, we have had a lot of industry-university and industry-academic-government joint reseaches and developments. In those, there are white Koji fungi as stated above, non-dark and non-black pigment Koji fungi , leucine acid high productive Koji fungi (received Tohoku Invention Recognition Invention Exhortation award 1990 fisical year), anti-fungi material “Asperatine”. The Institute of Biotechnology Applied to Eumycetes was established by investiment of the Biologic Specific Industry Investigation Promoting Government Organization 1994 and we are making rapid progress as general microbe starter maker.”

Brewing Society of Japan
“The Brewing Society of Japan was established in 1906 and was authorized as an incorporated foundation in 1915. Thereafter, for 85 years, the society has supported the progress and development of Japanese brewers by supplying pure yeast cultures, publishing books on brewing and performed other related duties.”

White Labs
“Every day, we set out on a single mission: To stretch the limits of science in order to set new standards in purity and freshness. From the industry’s first pitchable liquid yeast, to a complete revolution in the way it’s propagated and packaged, our innovative spirit is tireless.”

Wyeast Laboratories
“For over three decades we’ve been a leader in producing premium fermentation products. Our liquid yeast strains are recognized around the world, and we’ve partnered with some of the most successful craft beverage brands. But we’ve never stopped exploring new ways to ensure that every product that leaves our Hood River facility is of the highest quality possible.”