Keicho Tsuho coin (慶長通宝)

The Keicho Tsuho was a copper coin issued by the Edo Shognate in 1606. (different theories exist.)
In Japan, it was considered as the first mintage issued by the central government after many years, since the 'Kocho -Jyunisen' coin (the twelve types of coins minted by the imperial court) was discontinued in the Heian Period. The letters of '慶長通寳' was raised on it.

The coin had roughly two types of shapes.
One was comparably big and good quality with well-raised letters, and the other was small and bad quality, a private mint coin made in the molds which had originally been used for the 'Eiraku Tsuho coin' but were modified for the 'Keicho Tsuho coin' by changing the letters of 'Eiraku' to 'Keicho.'
The former was mostly used in around the Edo and Kyoto areas, and the latter was mainly used in the Kyushu area.

However, along with Sung coins, Ming coins, and Ryukyu currency, 66 Keicho Tsuho coins were excavated in the Kango remains in Sakai City. Some theories suggest that from around 1596 to 1597, the coins had been minted in Osaka, and in Sakai City, where cheap coins had been actively minted. Thirty Keicho Tsuho coins were excavated from the Nippara Limestone cave in Okutama-cho town in Tokyo as well.

Because nearly no documents about mintage at that time have been found, some theories deny the minting of the coin by the Edo Shogunate. However, considering the act enacted by the government in 1608 that banned the use of the Eiraku Tsuho coins, it is reasonable to think that other appropriate copper coins would have existed. In the next year, as Osadame soba (a system of officially fixed prices), the exchange rate was decided as one ryo of gold to 50 monme of silver to one kanmon of the Eiraku Tsuho coin to four kanmon of the 'Kinsen' coin.
This 'Kinsen' is considered as the Keicho Tsuho coin (some people say it was 'Bitasen,' low quality coins whose surfaces were worn away.)
Although the use of the Eiraku Tsuho coin was banned, the amount of mintage of the Keicho Tsuho was definitely not sufficient to substitute for the Eiraku Tsuho. Therefore, some theories say that this act was practically to prohibit the preferential use of the Eiraku Tsuho, which had been exchanged at the rate of one ryo of Gold to one kanmon of Ei.

The Edo Shognate had in fact just been established at the time, and it seems that the Keicho Tsuho coins were not distributed nationwide because Osaka and Sakai, the most economically developed cities, had been ruled by the Toyotomi Clan, who had felt hostility against the Edo Shogunate; the national economy had not been fully understood; and private low quality coins had been distributed.

Nationwide currency by the Edo Shogunate was not established until the Kanei Tsuho coin, which was issued after the Edo Shogunate established the government of the entire nation when the Toyotomi clan was ruined.

[Original Japanese]