If there are two things Japan takes very seriously, it's business and comic books. And it's the rare personality who makes a splash in both realms. Rarer still if he's a gaijin (foreigner).

In 1999, Carlos Ghosn took a job many thought was impossible: reviving money-losing Nissan Motor Co. The odds were stacked against a Brazilian-born, Lebanese-raised Frenchman, then 45, succeeding in insular Japan. By 2001, Ghosn was beating them by axing tens of thousands of workers, closing factories, chopping weak affiliates and shaking up a rigid management structure. That year, the best-selling "True Life of Carlos Ghosn" manga series hit bookstores.

Fifteen years later, investors are hoping he can repeat that feat at Mitsubishi Motors Corp. On Wednesday, Ghosn formally added the scandal-plagued company to his already full schedule steering Nissan and Renault S.A. Yet turning around Mitsubishi may be Ghosn's biggest challenge to date as a fudged fuel-economy-data scandal dents sales and revenues. What's more, Mitsubishi suffers from a relevance problem that predated its devastating Volkswagen moment.