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 positioned underneath the sheet. 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 while in this comfortable bed.
The origins of the Japanese heated table can be traced to the 14th-century Japanese irori or cooking hearth. By the 17th century, irori dug into the ground, called hori-gotatsu, resembled a fixed kotatsu. Modern heated bed tables, which are moveable, are referred to as oki-gotatsu. Since most Japanese homes have little insulation and no central heating, kotatsu serves as efficient space heaters during the colder months. And though similar heating devices were, and sometimes are still used in many countries, the kotatsu is thought to be the first contraption of its kind. Also, this ingenious Japanese furniture piece might be a predecessor to floor heating as we know it.