The Oban was a large gold coin - with the most popular varieties weighing between six and eight ounces - used in medieval Japan during the Edo period of 1603-1868. At this time Japan was effectively ruled not by the emperor, but by the shoguns from the Tokugawa clan. The oban was frequently used to reward a family for their special favor to the shogun, or as a gift from one clan to another in response to a particularly favorable marriage.
Images courtesy of the American Numismatic Society.
Oban were used to represent the wealth of an entire family or clan. The oban coins were frequently stored in mints (called kinza for gold mints or ginza for silver mints), and could be stamped to show mortgages, liens, or loans borrowed against the family's oban holdings for investment purposes. Despite its desirability, the oban was not commonly used by Japanese people. The primary currency for day-to-day transactions were copper coins known as zuni, which were often imported from China. With the end of the Tokugawa shogunate and the restoration of the power of the emperor, oban fell out of use. They were replaced by the Yen, a silver coin that was minted at parity to the US dollar. Today, oban are highly sought after by collectors - Japanese and Western alike - both for their beauty and symbolic representation of the importance of saving and planning.