In 1853 the Edo bakufu (Japanese feudal government headed by a shogun) was forced to open its port as a result of the arrival of Kurofune (The Black Ships of Commodore Matthew Perry) at Uraga offshore, and on June 12, 1854, a negotiation was started at Ryosen-ji Temple in Shimoda City concerning exchange rates between Japanese and Western currencies.
嘉永6年（1853年）、浦賀沖の黒船来航により江戸幕府は開港を迫られ、安政元年（1854年）5月17日より、下田市了仙寺にて日本貨幣と西洋貨幣との交換比率の交渉が行われた。