TOKYO—Mazda Motor Corp.’s new CEO minces no words about his top priority for the future. “In terms of profit and brand, the U.S. is the highest priority,” Akira Marumoto, 60, said at a press conference last week after being named the company’s next leader, effective June 26.

He has had five years to focus on that challenge, as he has been Mazda’s Americas chief since 2013. Marumoto has overseen the ramp-up of one assembly plant in Mexico and brokered the plans for another in Alabama—all while struggling to build both brand value and volume in Mazda’s most important market.