Japanese auto giant Nissan (NSANY -0.14%) was having a so-so year in the U.S., with sales up about 7% -- until May. Last month, Nissan's U.S. sales jumped 25%. What changed?

It turns out that Nissan's North American operation has a new boss, Jose Munoz. As Motley Fool contributor John Rosevear explains in this video, Munoz has big plans to gain ground in the U.S., thanks to the weakening Japanese yen -- and those plans should have Detroit worried.