Most houses use kotatsu(foot warmers) and oil, gas, and electric heaters. These days irori, hibachi or horigotatsu(not warmers fixed in a sunken floor) are seldom found in most Japanese houses.
A portable low table with an electric foot-warmer underneath, covered with a quilt.
The floor is cut in a square at the center of the room for the hearth, which is used for heating and cooking.
A ceramic brazier with charcoal inside, used for heating.