This is a hearth about 42cm square that is cut into the tea room floor. Usually the walls of the hearth are plastered. The hearth is cut into the host's mat for mukogiri (in the corner adjacent to the guest's mat) and sumiro (in the corner away from the guest's mat), and outside this mat for yojohangiri (four-and-a-half mat) and daimegiri (three quarter size host's mat). It is used to boil water in the tea room from the beginning of November to the beginning of May.