Nationwide, with the exception of Hokkaido (never been there but that's what I'm told).

To boot, the houses/apartments here are: NON-insulated (no, seriously -- my outside house walls are 1/2 a foot thick), use single-pane, thin glass for windows and doors, and are ridiculous to keep warm in winter or cool in summer. Within 15-20 minutes, the room is the same temp. as the outside air.

IMO, completely ridiculous considering Japan is supposed to be an industrialized, first-world country. I'm freezing my goolies off in my neanderthal shack, yet surfing the web on my 100MBps fiber optic broadband line... Go figure!