Mameitagin 'Ansei Mameitagin' Large 政

Struck in the chaotic years immediately following the Harris Treaty of 1858, the Ansei Mameitagin was the Shogunate's direct response to a currency crisis of its own making. Foreign merchants — primarily American and European — were legally exchanging Mexican silver dollars for Japanese gold koban at ratios that drained the country's gold reserves at an alarming rate. The Shogunate's answer was mass debasement: silver content slashed to barely above symbolic levels.

The resulting domestic inflation was severe enough to accelerate anti-Shogunate sentiment among samurai classes who watched their stipends collapse in real value. Production ceased in 1865 as the Keio-era recoinage superseded it.