person in charge of warming sake
Refers to a staff member at a bar or restaurant whose job is to heat sake to the proper temperature. A specialized term mostly used in traditional drinking establishments.
At that izakaya, the sake warmer heats the sake to the perfect temperature.
Compound of 燗 (kan, 'warming sake') and 番 (ban, 'person on duty'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the role.