A place where sake is brewed or stored is called a Sake-gura (sake brewery house).
A reasonable amount of mold is necessary to make sake.
Different brewery houses create different sakes even when they're in the same area. This is because the environment of each brewery is different, and its mold will interact with the brewing process to create unique flavors and aromas even if the variety of koji mold is the same used in other breweries.
Les grands sakes de Hiroshima