Before his unification of the whole country, Ieyasu TOKUGAWA had planned to issue a form of currency for general distribution that would be smaller than the oban and would have an engraving instead of ink writing.
天下統一に先立ち、徳川家康は大判より小型のもので墨書を極印に改め一般流通を想定した通貨を発行する構想を持っていた。