horizontal stone hand mill
A traditional stone mill consisting of two flat, round stones; the upper stone is rotated by hand to grind grains or beans. Often used in historical or cultural contexts.
In the old days, people ground soybeans with a horizontal stone hand mill to make kinako.
Compound of 平 (hira, 'flat') and 臼 (usu, 'mortar, mill'). The exact historical derivation is uncertain, but the name describes the mill's flat, horizontal design.