Keeping warm in Japan in Winter is big business.
Look at this for example. Central heating is scarce, so people use many ways to keep warm. The biggest traditional way is the kotatsu, which I mentioned last post. I bought one finally, and I absolutely love it. It is a table with a heater under it, and a blanket is used to trap the heat. You would think only having your legs in the heat would make the rest of you cold, but it's not too bad. People will often recline and pull up the blanket for a nap, staying nice and toasty. I like it because it doubles as my workspace, as you can see in the picture:
The blanket and plug can be removed, thus making it a regular table in the off-season. I am a convert to the kotatsu, which is a definitely a Japanese idea only. I considered heated carpet and electric blankets, but the idea of being toasty and having a bigger table (there is a tiny apartment wall table folded up behind the chair) was the deal breaker. There are so many options. People use kerosene heaters, bottles you can microwave or put warm water in and stick in your bed, stomach warmers (it looks like a scarf for your waist), Snuggie rip-offs, you name the body part and they have those instant heat packets for it.... I'm happy with my kotatsu.