Which style of sake is only ever served chilled?

The style of sake that is only ever served chilled is sparkling sake. Sparkling sake is produced using a method that creates natural carbonation, often leading to a refreshing, fizzy quality that is best enjoyed chilled. Serving sparkling sake cold enhances its vibrant flavors and effervescence, making it an appealing choice for warm weather or festive occasions.

Junmai, futsu-shu, and daiginjo are all styles of sake that can be served at various temperatures, including chilled, room temperature, or warm, depending on personal preference and the specific characteristics of the sake itself. Thus, while those styles can indeed be enjoyed chilled, they are not exclusively served that way, unlike sparkling sake.