There's nothing like the serenity of a ryokan, a traditional Japanese inn. Note the kotatsu, a low wooden table covered with a futon. A heat source beneath heats the space under the table; the surrounding comforter holds in the warmth. Putting your legs under such a table is a wonderful way to keep warm efficiently. It works especially well if you are wearing a traditional samue, as I am. The heat rises through the garment's open bottom and exits the neck, keeping the whole body warm. But on this pleasant May evening, extra heat was not necessary.
From Shrines and Serenity in Japan