Ara-yachi is a kind of Tsuboya ware that is unglazed, or coated with mud or maganese glaze, and then is fired at about 1120℃. Ara-yachi ware includes large items, such as storage jars for water, miso (bean paste), or liquor, and small ones, such as masubin, a bottle for measuring awamori.

The genealogy of ara-yachi ware becomes clear by tracing the lineage of earthenware mortars. Depending upon how the inside of the mortar is patterned with parallel grooves, whether the narrowed rim is extant, whether there is a pouring lip, and the shape of the body, modern mortars can be divided into five styles: I, II, III, and IV as illustrated on the right. Styles I and II can be found in Kina or China ware, while III and IV can be ascribed to Tsuboya ware. At the site of the Wakuta kilns, there has been another discovery of mortars which are believed to be older than those of Kina or Chibana ware.