This is how the Japanese stay warm in the winter, or how you can stay in bed all day!
The 'kotatsu' consists of a blanket placed between a low table-frame and table-top, with a heat source placed underneath the blanket. With your legs placed under the blanket, someone wearing traditional Japanese clothing would have warm air come through the bottom of their robes and exit around the neck, heating the whole body.
The origins of the kotatsu can be traced to the 14th century Japanese irori, or cooking hearth. Since most Japanese homes have little insulation, kotatsu serve as effective space heaters during the cooler months.
Source / Photos: Belle Maison