A kotatsu 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.
A modern Japanese kotatsu
The underside of an electric kotatsu, with the heater visible in the centre
Edo-period kotatsu at the Fukagawa Edo Museum
Mametan [ja] coal briquettes mostly used in the early twentieth century
A brazier is a container used to burn charcoal or other solid fuel for cooking, heating or cultural rituals. It often takes the form of a metal box or bowl with feet. Its elevation helps circulate air, feeding oxygen to the fire. Braziers have been used since ancient times; the Nimrud brazier dates to at least 824 BC.
Brazier with burning fire in a rune stone circle at a summer solstice
A brazier being used to grill chicken and steaks.
Ancient Greek brazier and casserole, 6th/4th century BC, exhibited in the Ancient Agora Museum in Athens, housed in the Stoa of Attalus
Simple box-style brazier, with broad grill, intended as a metal container (e.g. kettle/tray) heater/cooker
![Mametan [ja] coal briquettes mostly used in the early twentieth century](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Japanese_CoalBriquettes_Mametan_02.jpg/640px-Japanese_CoalBriquettes_Mametan_02.jpg)
