The electric kotatsu, a table with a built-in heating unit on its underside, first appeared in the latter half of the 1950s. Today, most kotatsu are electric. A quilt is sandwiched between the table frame and tabletop.
There are two types of kotatsu - the low type placed on the floor and the hori-kotatsu type in which the table frame is placed over an opening in the floor about 40-centimers deep in which one sits with feet in the opening. More recently, there has also appeared a high-table type of kotatsu that can be used with chairs instead. An average of 1.2 million kotatsu are sold every year.