​Kosaka Brewery was founded in 1913 and is located along the banks of the Ishiyori River, a tributary of the Sunagawa River. This region has long been renowned as a fertile rice-producing area and is notably the birthplace of the esteemed Omachi rice, often referred to as the "phantom sake rice." The area is dotted with numerous agricultural reservoirs, which historically attracted many cranes seeking water. The brewery's flagship brand, "Tsurunoike" (Crane's Pond), derives its name from the local ponds where cranes once gathered and uses locally grown rice nourished by the same waters. For brewing water, the brewery utilizes soft well water sourced from stable geological formations near the mountains. In their koji-making process, they employ traditional koji rooms surrounded by "sukumo" (rice straw mats) with natural ventilation, allowing the koji mold to develop slowly and enhancing the rice's natural flavors. Additionally, they use traditional Japanese kettles for steaming the rice, preserving time-honored brewing methods.​