The Tokugawa government first commissioned in 1768 a Kan'ei Tsuuhou coin valued at 4 mon. The first version was made at the Fukagawa mint in Edo and had a design of 21 waves on the back of the coin (see image above). In 1769 the design of the reverse changed to have only 11 waves and all subsequent versions used the 11 wave design. It was not much larger than a 1 mon coin (27-28 mm vs 25-26 mm) and so it was cost effective to produce. This was desirable in a time when there was a growing scarcity of copper. Because the economy itself was usually growing in this period the coins were readily accepted by users. The government ordered a new batch of this same coin made in the period 1821-1825. These are largely identical but the quality is much more varied, which is to say that many of the 4 mon from this era are of poor manufacture. The metal content of these also tend to be more on the reddish side than the earlier coins which have a higher admixture of other metals than copper. Because these coins were manufactured in the Bunsei period (1818-1829) They are called Bunsei coins by collectors, in contrast to the earlier ones which are called Meiwa coins (from the Meiwa era 1764-1771). The Bunsei coins are as common as the Meiwa coins. One more period of minting was in the Ansei era (1854-1859). There is variation but they tend to be on the yellowish brassy side and the file used to smooth the face is very rough, leaving clear file marks on the face. In 1860, under grave financial difficulties the Tokugawa government began minting the coin in iron but this was relatively unsuccessful and the coins are moderately uncommon.