A traditional Japanese unit of volume, equal to about 180.391 liters (39.68 British Imperial gallons or 6.37 cubic feet). The unit originated as an estimate of the amount of rice needed to feed a person for a year
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}