Tsubo : An informal unit of area used in Japan to measure area inside buildings. One tsubo is an area of about 3.3 square meters (3.95 square yards), an area that can be covered neatly by two traditional tatami mats. See tatami, above
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}