貞観永寳 (Jōgan Eihō) (“Everlasting Treasure of the Jōgan Era”) // Plain. 19.4mm, 2.0 grams. Hartill, Early Japanese Coins (2011), nos. 1.55–1.58; The Standard Catalog of Japanese Coins, JC 01-9.

Graded 80 (aEF or so) and certified.

The Jōgan Eihō was introduced in Jōgan 12 (870 CE) and belongs to the celebrated early Japanese Kōchōsen (“Imperial Court Coinage”) series. These official issues were modeled on the Chinese cash-coin tradition and represent some of the earliest indigenous coinage of Japan. By the later ninth century, diminishing supplies of copper and the declining monetary economy resulted in increasingly small and debased coins; the Jōgan Eihō is characteristic of this late phase of Japan's ancient coinage. It was succeeded by the Kanpyō Taihō in 890 CE. The imperial copper coinage continued only intermittently thereafter, ending with the Kengen Taihō issue of 958, after which Japan ceased producing a regular domestic coinage for several centuries.

A scarce and historically important coin of early Heian-period Japan.