Owner Comments:
JNDA 02-10. This is a 'new' denomination first minted after the close of WWII, and after the establishment of the new, current, constitutional monarchy. (The previous 5 yen was a gold coin and not a common use coin). Appropriately with the new government established, the building featured on the reverse is the Parliament or Diet building
The JNDA places this coin under the 'current coinage' section of the catalog, which refers to the coinage issued under the new government as established by the post-war constitution. (Current as opposed to 'modern' which refers to any of the coinage established under the Meiji restoration going forward--minted in the western style, with western type equipment). So, it is current in the sense that it was minted under the auspices of the current constitutional monarchy.
The legend on the coins now read 'Nippon koku' or 'Country of Japan' vs. the previous 'Dai Nippon' (Great Japan) or 'Nippon seifu' (Government of Japan)-- the latter a temporary status until the new constitution was developed. The legend and the coin dates are now exclusively read left to right vs. the pre-war right to left. There are smaller denominations (50 sen and 1 yen) minted in the same years that utilized the new legend as well, but are included under the 'old' coinage (section 01 in the JNDA), perhaps because these denominations were already in existence for common usage. So, that makes this 5 yen coin the official earliest dated 'current coin' in the catalog system.
Though both modern and current as these are defined for Japanese coinage, this 5 yen is not a circulating type coin. It was minted for two years only, S23 and S24 (1948-1949). The coin was replaced by one with a new design and of lighter weight in S24 (1949).
Diameter 22 mm, brass, weight 4.00 grams.