Name and Classification
In the collection catalogue of the Currency Museum (taken from the book "Zuroku Nihon no Kahei"), this silver coin is listed under the name "Bunsei Nanryō Nishu-gin." In a Ministry of Finance record from the early Meiji period (1875), it is written as "Bunsei Nishu-gin." It was also commonly called "ko-nishu" (small two-shu), because it was smaller than the Meiwa Nanryō Nishu-gin (according to the Seisenban Nihon Kokugo Daijiten dictionary). The face value is two shu. Eight two-shu silver coins equal one ryō of gold (according to the Currency Museum catalogue). Unlike chōgin, which were weighed when used, it is a silver coin counted by number.
When It Was Minted
According to the Ministry of Finance record (1875), minting ran for seven years, from Bunsei 7 to Tenpō 1. The amount minted was 7,587,000 ryō. The specimen held by the Edo-Tokyo Museum is also dated Bunsei 7 (1824). At this time, the shogunate was carrying out the Bunsei recoinage (from 1818). According to the Currency Museum, it was a recoinage to make up for the shogunate's financial difficulties, and it led to rising prices.
Inscriptions on the Two Sides
In the image in the Currency Museum's collection catalogue, one side bears an inscription stating that eight pieces of nanryō silver are exchanged for one koban ryō, and the other side bears the words "Ginza Jōze." The same wording appears on the Meiwa Nanryō Nishu-gin, and the Currency Museum explains its meaning as "eight pieces are exchanged for one koban ryō." "Nanryō" means good-quality silver (according to the Currency Museum catalogue).
Size, Fineness and Weight
The specimen held by the Edo-Tokyo Museum measures 1.9 cm × 1.5 cm. The fineness and the weight have not been confirmed in the public sources checked. For this reason, this article does not give these figures.
Changes in Two-shu Silver Coins
The following list is based on the Currency Museum catalogue and the Ministry of Finance record. - Meiwa Nanryō Nishu-gin: issued in 1772. Fineness 98%. - Bunsei Nanryō Nishu-gin: minted from Bunsei 7 to Tenpō 1. - Ansei Nishu-gin: issued in 1859. Fineness 85%. Another silver coin of the Bunsei period is the Bunsei Nanryō Isshu-gin (1829, fineness 99%). About the Meiwa Nanryō Nishu-gin, the Currency Museum catalogue explains that it was issued as a silver coin counted in units of gold coins, and that it became a subsidiary coin to gold.
How to Check a Coin in Hand
First, measure the size and compare it with the value above. Next, check the inscriptions on both sides. The Meiwa Nanryō Nishu-gin also bears the wording that eight pieces are exchanged for one koban ryō. As its nickname "ko-nishu" shows, the Bunsei coin is smaller. The difference in size is a clue. To judge whether a coin is genuine, an appraisal by a specialist is the reliable way. How to spot forgeries is covered in An Introduction to Spotting Forgeries. For related entries, see Nanryō Nishu-gin, Nishu-gin, The System of Edo Silver Coins and Bunsei Koban.