Japan's stealth manipulation of the yen is proving successful. Last week, Japan's finance minister told their Parliament that the government would intervene in currency markets if they yen strengthened. So... this week the yen declined from 109 yen vs dollar to 110.
Why? Banks, governments and private firms trading in foreign exchange markets are not going to buy yen (which cause strengthening) if the force of the Japanese government has publicly declared that the yen won't rise. That would be a stupid trade. So they will sell the yen, because the value is almost certain to be lower or neutral. When they sell, it causes the yen to go down. So the Japanese government gets what it wants without intervening.
The yen devaluation makes Toyota, Honda, Mitsubishi and other national champion firms big money. They don't have to actually be better than their global competitors to make a profit if the government simply lowers the yen price.