The 1st generation Shima Kahei, a potter of the Daigo kiln, produced this type of earthenware, which included Raku ware tea bowls, through a recommendation from the 58th generation Matsukura Shoei from Ryoanji Temple.
The bottom of the cursive “Ryoanji” mark contains the rounded square “Rakuami” mark. “Rakuami” comes from the name of “Rakuami” that was given to the 1st generation Kahei.
