Zeniza is an organization or agency which minted coins including Kanei Tsuho during the Edo period.
The organization which was established during the Aska period for the purpose of minting Kocho-Junisen (twelve coins cast in Japan) emitted from the Nara to Heian period was called Jyusenshi.
In the early Edo period, mintage of coins including Kanei Tsuho was conducted mainly by private contractors, based on the bakufu's approval. That is, when there was a demand for coins, the bakufu publicly sought contractors who were willing to mint coins, and placed an order for coins with a definite deadline with those who were capable of mass production of coins. When the sufficient number of coins was produced, zeniza was dissolved. Such contractors included Gofuku-ya kimono shops, itowappu nakama (the thread tally union), officers of gin-za (an organization in charge of casting and appraising of silver during the Edo period) and other influential townspeople. Zeniza was made to pay to the bakufu 5 to 20% of the amount of mintage, about 10% in principle, as Unjo (one of the taxes which were assessed on workers in all kinds of industries except for the agriculture industry). But Kanei Tsuho, minted by more than sixty zeniza all over the Japan, was of great variety in production and raw materials, and lacked integrity of appearance.
As kin-za (an organization in charge of casting and appraising of gold during the Edo period) and gin-za concurrently took charge of mintage of coins after 1765, zeniza was established as a fixed guild and the bakufu strengthened the control of mintage and tried to homogenize coins. After the Genroku era (from 1688 to 1703) production of copper began to decline and the bakufu was running out of copper for export, which was one of the reasons the bakufu strengthened the control of mintage.
Kanei Tsuho was born when Shinsuke SATO, a wealthy merchant in Mito City, asked the bakufu and the Mito Domain for permission to mint copper coins due to a short supply of coins in 1626, and was granted such permission. It is said that Kanei Tsuho which was called Nisuiei was minted at that time. Although Kanei Tsuho was no more than privately-minted coins at this point, possibly Keicho-tsuho in 1606, which was said to be ordered by the bakufu, and Genna Tsuho, minted in 1617 were on the same level with Kanei Tsuho.
Ten years after, in 1636, it was decided that the bakufu carried on a full-scale operation of mintage of Kanei Tsuho as a result of an increase in production of copper from copper mines including Ashio Copper Mine, and three zeniza were established; Hashiba in Asakusa, Edo, Tsuna-nawate in Shiba (Minato Ward, Tokyo) and Sakamoto in Omi Province (Otsu City). In 1637, for the purpose of securing the sufficient number of coins for circulation, in addition to the three zeniza stated above, eight more zeniza were established in Mito, Sendai, Mikawa-Yoshida domain in Mikawa Province, Matsumoto City, Takada City, Hagi City in Nagato Province, Okayama City in Bizen Province and Takeda City in Bungo Province. In addition another zeniza was established in Inomiya, Suruga Province in 1639, but mintage was temporarily prohibited in all the zeniza in 1640 because of a drop in the value of a copper coin in the previous year, and because many coins were too light.
In 1656, however, in order to make up for scarcity of coins due to the subsequent economic development, the bakufu established zeniza in Torigoe, Asakusa, Edo (Taito Ward) and in Kutsunoya, Suruga Province and ordered mintage. It is said that zeniza was also established in Kennin-ji Temple in Kyoto in 1653, but it is uncertain. Kanei Tsuho which had been minted by this time was called Kokanei, and had a better quality than imported coins which had been widely circulated.
As the bakufu prohibited Kanei Tsuho from being exported in 1659, zeniza in Nakajima, Nagasaki City minted copper coins imitating Chinese coins only for the purpose of international trade, and those coins were called Nagasaki Boeki-sen.
Later, during the period from 1668 to 1683, Nuinosuke GOTO, Gofuku-ya kimono shop, undertook mintage, establishing large zeniza in Kameido, Edo, and Kanei Tsuho which was minted in this period, called Bunsen, had homogeneous and excellent qualities. Zeniza in Kameido also minted coins during later Genroku and Hoei eras, from 1714 to 1718, and during Gembun era.
Because the value of copper coins rose against that of gold and silver coins, whose quality level had decreased and whose circulation had increased since the remintage of koban (oval gold coin) and Chogin (collective term for silver), and also because Besshidozan Copper Mine started to produce more copper, zeniza was established in Shichijo by members of itowappu nakama (the thread tally union) in Kyoto from April 1700 to January 1708 to mint a thin and small type of Kanei Tsuho, and Hoei Tsuho after February 1708. Kanei Tsuho which was minted in Shichijo, Kyoto and also in Kameido, Edo after 1697, was called Ogiwara-sen, being turned into a thin and small type as a result of policies set by Shigehide OGIWARA.
Furthermore, after 1714, zeniza were established to mint Kanei Tsuho in Kameido (Edo), Aikawa-cho (Sado Province), Juman-tsubo (hundred thousand tsubo) in Fukagawa, Edo (Koto Ward), Nanba (Osaka), Sendai, Yodo Toba Yokooji (Outskirt of Kyoto), Koume (Edo), Sarue (Shimousa Province), Uzu (Kii Province), Fushimi, Nikko City (Shimotsuke Province), Ani Copper Mine in Akita, Ishinomaki, Fujisawa City (Sagami Province), Kozu (Osaka) and Ashio (Shimotsuke Province). The bakufu tried to specify the location of mintage by making letters indicating the location of mintage cast on the back side of coins and by making letters on coins different according to the location of mintage, for the purpose of maintaining the quality of coins and strengthening copper regulation, which was in urgent demand.
After 1765, zeniza was brought under control of kin-za and gin-za and became a fixed guild of mintage, a permanent organization different from before. Some of the old local zeniza continued mintage, but they were also brought under control of kin-za. After that, Kanei Tsuho was produced mostly in iron, and a great number of iron coins were minted in zeniza in Kameido, Fushimi, Ishinomaki and Ota City, Hitachi, Hitachi Province which were under direct control of kin-za. Copper coins were minted especially for international trade in Nagasaki after 1767, but their quality was poor.
Under the policy set by Hisataka KAWAI, Kanei Tsuho Shimonsen brass coins started to be minted in Shinden, Fukagawa-senda (Koto Ward), Edo under the control of gin-za after in 1768. In 1821 zeniza in Hashiba, Asakusa started to mint Shimonsen coins, and after 1865 zeniza in Morioka, Sendai, Mito, Tsu City (Ise Province) and Hiroshima City (Aki Province) minted Shimonsen iron coins.
Furthermore, under the policy set by Sanemon GOTO, okane-aratame-yaku (a money inspector), Tenpo Tsuho started to be minted in kin-za and Hashiba, Asakusa in 1835. Tenpo Tsuho was also started to be minted in Nanba, Osaka in September 1865. Kao (written seal mark) of Shozaburo Mitsutsugu GOTO of kin-za was cast on the back side of this Tenpo Tsuho.
Bunkyu Eiho was minted in zeniza in Higashi-Daiku-machi, Fukagawa, Edo under the control of gin-za in March 1863, and also in zeniza in Masaki and Kosuge under the control of kin-za in January 1864.
First, the prescribed amount of raw materials, that is, copper, tin, lead and shirome (antimony or bismuth), was measured, dissolved in crucibles and made into alloy. Raw materials of 14 kan (unit of volume, approx. 3.75 kg) were processed at a time as hitohuki (one blow), and the alloy thus produced was crashed, divided into lumps of 500 monme (a unit of weight, approx. 3.75 g) and sent to Zenibuki-sho. This process was called Obuki.
Next, matrix coins, which would serve as a mold, were pressed onto the sand, routes in which melted copper would flow were made on the sand, and then the sand was burned and made into a mold. A pair of molds, which were made for each side of coins, were bound together, and melted copper was poured between them with the use of an infundibulum.
A matrix coin, which was a prototype of a coin, was made by using a hand-carved matrix coin, and mass production of homogeneous coins was made possible by the process of transcriptive molding from a carved matrix coin to a tin matrix coin, then to a copper matrix coin, and then to a coin in currency.
After cooling, a so-called edasen (money tree), which consisted of many coins at pointed ends of the sprue runner rod, could be taken out of the molds. Coins were removed from edasen, threaded onto a rectangle section bar, and the edges of coins were filed at one time in order to get rid of burr (disambiguation). Furthermore, in a process called 目戸切, the hole at the center of a coin was finished, and then a coin was boiled in a bean soup in order to remove sand which was attached on it and scuffed with a rope in order to gloss it.
When finished, coins were sent to the inspection center, and accepted coins were threaded, made into a bundle called zenisashi and then stored in the kanegura (gold storehouse). Coins were issued by selling them to ryogaesho (money exchangers) in accordance with their current market value.