noun
one-yen bill
Refers to the historical one-yen banknote; no longer in circulation.
祖父の引き出しから古い一円札が出てきた。
An old one-yen bill came out of my grandfather's drawer.
一円玉 is the one-yen coin currently in circulation, while 一円札 is the historical banknote.
Compound of 一 (いち, 'one'), 円 (えん, 'yen'), and 札 (さつ, 'bill').