What is the currency used in Japan?

The currency used in Japan is the yen. The yen is the official currency recognized globally and is represented by the symbol ¥ and the code JPY. It is one of the most traded currencies in the world and serves as a key representation of Japan's economy. The yen has a long history and is widely accepted for transactions within Japan, encompassing everything from daily purchases to international trade.

The other currencies mentioned do not apply to Japan. The dollar refers to various currencies used in countries like the United States and Canada, while the pound typically refers to the British pound sterling. The euro is the official currency for many European countries but does not have relevance to Japan’s financial system. Thus, yen is definitively the correct answer in this context.