1 Bu 'Ansei Ichibu Kin'

The Ansei Ichibu Kin was not a new denomination but a debasement response. By the 1830s, the Tokugawa fiscal system was under sustained pressure — crop failures, peasant uprisings, and the costs of coastal defense drained the treasury. The Kinza reduced gold content from the earlier Bunsei issue's already-compromised alloy, continuing a long slide that had begun in the eighteenth century. Each successive ichibu issue contained less gold than the last, a pattern the merchant class tracked closely and exploited through currency arbitrage.

The series ended abruptly when American and European trade treaties forced Japan to confront its artificially distorted gold-to-silver ratios against world markets — triggering a monetary crisis that accelerated the Shogunate's collapse.