Winter is particularly cold in Japan, and although it isn’t much different to the UK it is difficult because you feel it constantly.. The buildings aren’t typically insulated (especially not my jutaku!) and the windows aren’t double-glazed. So whatever the temperature is outside, you can guarantee the inside of my house is about the same!
That’s where “kotatsu” become a joy. Kotatsu are tables which have a heater underneath, and a removable table top which sandwiches a thick, snuggly blanket under it and the table structure to keep the heat in. It is such a pleasure in winter to sit under the kotatsu and keep warm.