The Japanese Yen is often influenced by overseas fluctuations (rather than domestic), and will fluctuate depending on the trends of foreign currencies.
The Japanese Yen is most influenced by the American dollar.
The USD is the most common and frequently used currency for international trade and investment.
Therefore, domestic American economic indicators, regulation news, corporate news, and military news are all fundamentals that influence the exchange markets.
The Euro is the common currency for 18 European countries and territories.
With Germany and France having the most power to set trends, the Euro is the world's second most influential currency behind the USD.
The British Pound was once an important currency for economic trade, but in modern days it is less frequently used for imports and exports, and therefore it is used mostly for speculation purposes.
Therefore, because of its smaller volume, the change in value can be drastic.
Australia is known for its rich natural resources and also for the drastic changes of those resources.
Even as a less prominent currency, the AUD offers large changes in value, providing possible large profits.