ōban were made of hammered gold with a face value of 10 ryō (ounces). The word ōban means 'large stamped [piece]' in Japanese. The earliest ōban were made in the 1580s, when the feudal lord Toyotomi Hideyoshi (1536/7-98) co-operated with wealthy merchants in the Kansai district of central Japan and monopolized Japan's metal mines. He then began to mint gold coins of fixed quality.
The earliest ōban had no inscription - ideal for forgers. To overcome this problem, inscriptions and stamp marks were added. By 1586, the value of the ōban and the signature of the Goto family (the hereditary superintendents of the mint) were handwritten in ink on the front of the ōban. A flower stamp (hanaoshi) was also impressed on the surface. The stamp featured the crest of the paulownia flower (kiri) crest, which was later used in official government and imperial seals.