Kanshu (cold sake) (寒酒)
It is the sake (Japanese rice wine) created using the cold temperature of winter, one of the shikijozo (sake brewing in all seasons) techniques used until the early Edo Period. It became the basis of kanzukuri or kanjikomi at Itami, the center of sake production at that time.
Kanzukuri (Kanjikomi) that uses an area's naturally low winter temperature without incorporating modern ventilation systems, has been handed down or revived in various areas, but sake made with such methods is rarely called 'kanshu' nowadays.
The shikijozo production system was incorporated in the annual cycle of people of the early Edo Period similar to the 'seasonal' or 'natural' vegetables or fish of nowadays, and the sake that was made with kanzukuri process was treated apart from other sake, but the custom has disappeared now.
The current 'kanshu' is a term that refers to not just nihonshu but to the customs, atmosphere, and economy of the Edo Period.