We have officially entered the cold time of year here in Tokyo, when to wear a hat is to feel as one normally does without a hat and to not wear a hat is to feel as one who wears a hat of ice. What I'm saying is I need to buy a hat.

One of the most enduring symbols of winter in Japan is the kotatsu*, an ingenious invention comprising a table, a heater underneath it, and a blanket on top to keep the heat in. Other countries may have invented and/or adopted methods like central heating and insulation to stay warm during the cold months, but a surprising number of my Japanese acquaintances are passionately attached to the "under the kotatsu is warm, everywhere else is cold" housekeeping system.

I suppose much affection will attach to any national method of not freezing to death with such a long history -- the Muromachi Period seems to be the generally accepted kick-off of the Japanese kotatsu (inspired by certain Chinese contrivances brought back to Japan by Zen monks**), which would make it a little younger than the European chimney, and indeed it does have similar connotations to the whitey fireplace: home, family, lazing. What it lacks are the connotations of romance and bearskin rugs; lovers sharing a kotatsu is a cozy image, not a passionate one, and for structural reasons it is far more difficult to make out with someone while you warm yourselves at a kotatsu than it is to perform a similar feat at a fireplace.

Speaking from personal experience I can say that it is so very warm within the kotatsu that the chill beyond its blanketic scope seems even harsher, setting up a terrible feedback loop and giving the device a certain comfy menace. Like a wily fairy, it offers what you want, and takes in return your ability to do without it.

Obligatory language note: According to the 日本語源大辞典, the kanji used to write kotatsu (炬燵, 火燵, etc.) are all ateji. It is most likely a direct borrowing from Chinese 火榻子, pronunced kwatahusi in Japanese at the time, which makes sense if it was originally a Chinese invention brought to Japan by those notorious foreign jargon importers the Buddhists.

Since the Great Importation, kotatsu have been too cozy for their own linguistic good -- they're now used as a mocking, disparaging element in words like kotatsu-byouhou ("kotatsu [military] tactics" -- pure theory, never tested in the real world) and kotatsu-benkei (basically the same thing as an uchi-benkei: someone who is meek and submissive while out in the world, but turns into a Benkei-like tough guy at home).

* Optional Wikipedia Warning Link: scatological jabber.
** "We may be ascetic, but we're not stupid".