The pair consists of two currencies: US dollar and Japanese Yen and both of them has preconditions for changes in the rates. Primarily, the Yen is under the influence of the Bank of Japan, which actions are mainly aimed at decreasing the price of Yen, since the low rate enables to make Japanese products more competitive in the world markets. Declarations by the US politicians about new restrictions on import of Japanese goods and technology also have a significant role because introduction of restrictions and duties causes sharp decline in the Yen rate.
Meanwhile, the USD rate is affected by several factors: change of lending rate, economic situation in the country, US credit rating and some other events, which you can find in the economic calendar. The currency pair USD/JPY is the one, which is hard-to-predict. At the same time high market volatility allows to gain from several dozen up to a few hundred of points due to just a single market move.
Risk warning: Trading in FX and CFDs entails high risk of losing capital.