1 Bu 'Man'en Ichibukin'

The Man'en Ichibukin was struck in direct response to a crisis triggered by Japan's forced opening to Western trade. Foreign merchants, recognizing that silver was undervalued relative to gold in Japan compared to international ratios, began systematically draining the country's gold reserves through arbitrage — exchanging Mexican silver dollars for Japanese gold coins at a ruinous rate. The Edo shogunate's solution was to dramatically reduce the gold content of the ichibukin, dropping it to roughly a third of its predecessor's fineness, which effectively ended the arbitrage but also signaled to the world that the Tokugawa financial system was under serious strain.

Production continued past the shogunate's 1868 collapse and into the early Meiji period, making some examples technically post-Edo issues from the same dies.