How to warm sake

The most reliable way to warm sake is slowly, in a tokkuri flask standing in hot water: about 40 °C for nurukan (lukewarm) and about 50 °C for atsukan (hot). A microwave works too, if you heat in short bursts and check as you go.

How warm?

Warm sake has a name for every 5 °C, from hinata-kan at 30 °C to tobikiri-kan at 55 °C and above. The warmer it gets, the quieter the aroma and the drier and sharper the finish. If you're unsure, start with nurukan, around 40 °C, where the rice's umami opens up.

In a hot-water bath

1. Fill the tokkuri to about nine-tenths. Sake expands as it warms, so don't fill it to the brim.
2. Bring enough water to reach the flask's shoulders to the boil in a pan, then turn off the heat.
3. Stand the flask in the water. For one gō (180 ml) of room-temperature sake, allow about 2–3 minutes for nurukan and 3–4 minutes for atsukan.
4. Touch the bottom of the flask: gently warm means nurukan, hot to hold means atsukan. A thermometer is the surest way.

A hot-water bath (yusen) warms the sake slowly and evenly, so the aroma stays and the taste comes out round.

In the microwave

• Use a heatproof tokkuri or a mug. No metal containers and no cups with gold or silver rims.
• At 500 W, one gō (180 ml) takes about 40 seconds for nurukan and about 50 seconds for atsukan.
• Microwaves heat the top faster, so give the sake a gentle swirl when it comes out. Heat a little less than you think and add 10 seconds at a time if needed.

Too hot?

Above about 60 °C the alcohol starts to sting and the aroma is lost. If it got too hot, let it stand for a moment before drinking.

Which sake to warm

• Good warm: junmai, honjozo, kimoto and yamahai, and aged sake. Warmth brings out their umami and body. Sake that gets better when warmed is said to be kan-agari.
• Usually served chilled: fragrant ginjo and daiginjo, and fresh namazake. That's a habit, not a rule: some people love ginjo lukewarm.

Chilled temperatures are covered in Temperature and how to drink.

Warmed, then cooled: kanzamashi

Sake that was warmed and has cooled down again tastes softer and smoother. It even has a name, kanzamashi, and some people warm sake just to enjoy it this way.