noun
one-yen coin
Refers to the physical 1-yen coin, the smallest denomination of Japanese currency.
財布の中に一円玉がたくさんある。
There are many one-yen coins in my wallet.
一円玉は軽くて水に浮く。
The one-yen coin is so light it floats on water.
Compound of 一 (いち, 'one') + 円 (えん, 'yen') + 玉 (たま, 'ball, coin'). The suffix 玉 is commonly used for coin denominations.