There were many changes in the business environments of sake industries especially from late 1980s, such as shrinking domestic sake consumption and regulation changes in its production and sales. Consequently, many sake breweries and traditional liquor retailers closed their businesses. Some small-size breweries, however, challenged to transform their business to produce and distribute high-quality sake with their own brand, and later to develop the overseas sales networks. Similarly, some of traditional liquor stores became specialized stores with wide selections of sake to avoid price competitions with power retailers. This study explores the characteristics of relationship between a sake brewery and their customers (domestic specialized liquor stores and foreign importers/distributors), and the roles of the characteristics for the brewery to diffuse its sake domestically and internationally, by in-depth qualitive research on a sake brewery (Shimizu Seizaburo Shoten in Mie Prefecture) and their customers in Japan and overseas.