The yen, an aluminum coin, is the monetary unit of Japan. One yen corresponds to 100 sen, although sen are not used in everyday life any longer.
Coins come in 1 Yen, 5 Yen, 10 Yen, 50 Yen, 100 Yen and 500 Yen.
Bills come in 1,000 Yen, 2,000 Yen (very rare), 5,000 Yen and 10,000 Yen. 
The yen was formerly made of silver. Its symbol is ¥.