TOKYO >> The Bank of Japan’s Currency Museum in Tokyo mainly exhibits currencies that have been circulated in Japan, including fuhonsen coins said to be the first ever used in the country, toraisen coins imported from China during the medieval period, and oban and koban (large and small gold coins).

The free museum provides an interesting focus on an overlooked piece of daily life. The museum demonstrates that money is a complicated system that has been created through trial and error.

The museum is run by the Institute for Monetary and Economic Studies, Bank of Japan. It opened in 1985 in commemoration of the bank’s 100th anniversary. The museum exhibits about 3,000 items, including currencies and banknotes.

After entering the museum, visitors will encounter a glittering display of gold coins produced during the Edo period (1603-1867), such as keicho oban, genroku oban and kyoho oban coins. The oval coins, which were often given as gifts, are about 6 inches long and 3.5 inches wide, weighing 5.8 ounces.

Each coin bears a seal inscribed in Indian ink — the signature of the Goto family, who produced the coins. As oban coins without the seal were of lesser value, the seal would be rewritten when the ink faded. The coins’ value was guaranteed by the Goto family and the Edo shogunate, which commissioned their production, and the coins were circulated based on such guarantees.

As gold and silver coins were in short supply during the Edo period, han (domains) across the country issued their own bills. Up through the early Meiji era (1868-1912), more than 200 kinds of han bills were issued, mainly in western Japan. The creditworthiness of a domain determined the value of its bills.

In 1871, the Meiji government established a new currency law and changed the currency unit from ryo to yen. At the time, a one-ryo bill issued by the Shinano Matsushiro domain (Nagano Prefecture) was converted into 0.889 yen, while a one-ryo bill issued by the Satsuma Kagoshima domain (Kagoshima Prefecture) was converted into 0.322 yen. To finance battles during the Meiji Restoration, the Satsuma domain issued so many bills that their actual value was less than the face value.

The museum also features foreign currencies that suffered extreme losses in credibility. After Germany’s defeat in World War I, the country’s Ruhr industrial district was occupied by foreign troops. Germany subsequently experienced rampant inflation, leading to a collapse in the value of the German mark in 1923. The denomination of banknotes increased rapidly, with 100 trillion mark notes entering circulation.

A conspicuously large stone is displayed near a staircase in the museum. The stone is a form of money called rai, which was used on the Micronesian island of Yap.

Rai were used for land and other transactions but were never physically moved; even units that had sunk to the ocean floor were used. Transactions involving the stone money were not recorded. The sense of trust between the seller and buyer is said to have guaranteed the currency’s value.