A is a low, wooden table frame covered by a futon, or heavy blanket, upon which a table top sits. Underneath is a heat source, formerly a charcoal brazier but now electric, often built into the table itself. Kotatsu are used almost exclusively in Japan, although similar devices for the same purpose of heating are used elsewhere, e.g. the Spanish brasero or Iranian korsi. History The history of the kotatsu begins in the Muromachi period or Ashikaga shogunate during the fourteenth century. Its origins begin with the Japanese cooking hearth, known as the irori. Charcoal was the primary method of cooking and heating in the traditional Japanese household and was used to heat the irori. By the fourteenth century in Japan, a seating platform was introduced to the irori and its cooking function became separated from its seating function. On top of the wooden platform a quilt was placed, known as an oki that trapped and localized the heat of the charcoal burner. This early ancestor to the modern kotatsu was called a hori-gotatsu. The word hori-gotatsu () is derived from the kanji (hori) meaning ditch, digging, (ko) meaning torch or fire, and (tatsu) meaning foot warmer. The formation of the hori-gotatsu was slightly changed in the Edo period during the seventeenth century. These changes consisted of the floor around the irori being dug-out into the ground in a square shape. The wooden platform was placed around this, making a hearth. Then the blanket was placed on top of the platform again, where one could sit with legs underneath to stay warm. The moveable kotatsu was created later, originating from the concept of hori-gotatsu. This kotatsu came about with the popular use of tatami matting in Japanese homes. Instead of placing the charcoals in the irori, they were placed in an earthen pot which was placed on the tatami making the kotatsu transportable. This more modern style kotatsu is known as the oki-gotatsu. The word oki-gotatsu () is derived from the kanji (oki) meaning placement, meaning torch or fire, and meaning foot warmer. In the middle of the twentieth-century charcoal was replaced with electricity as a heating source. Instead of having the moveable earthen pot of charcoals beneath the kotatsu, it was possible to attach an electric heating fixture directly to the frame of the kotatsu. By 1997, the majority (approximately two-thirds) of Japanese homes had the modern irori and