There are at present about 1,700 sakagura, or sake breweries, in Japan. This number is dropping somewhat quickly, with several kura going under each year. But for those 1,700-odd kura brewing again this year, just about now is when the brewing season begins.
As you read this, thousands of brewing personnel are en route from their snowy homelands in places like Iwate and Niigata and the backwoods of Hyogo to the sakagura where they are employed to brew -- their home for the next six months or so.
Long ago, that is about a millennium ago, as sake brewing slowly began to spread from just temples and shrines to the general (tax-paying) business world, most breweries were operated by owners of fairly large tracts of land. Often (but not always), sake was brewed with rice that did not get sold or used during the year.