Two days before Mitsubishi Motors Corp. went public with news it had overstated the fuel economy of its cars, Chairman Osamu Masuko visited Nissan Motor Co. President Carlos Ghosn for a mea culpa. It did not take long for talk to turn from an apology to a deal.

Three weeks after Masuko and Ghosn's April 18 meeting, their respective boards signed off on an agreement in which Nissan will buy 34 percent of Mitsubishi Motors for about ¥237.4 billion. In purchasing the stake, Nissan will serve as a backstop for an automaker facing a mileage-rigging scandal that is threatening its existence.

Ghosn assured his MMC counterpart that Nissan "would back us up as much as possible, so hang on," Masuko, 67, said in an interview Thursday. The two companies first agreed to form a joint venture for minicars in 2010 and had discussed deepening ties over the years. It took Nissan discovering discrepancies in the performance of the models Mitsubishi Motors supplied — and the existential crisis that followed — to push negotiations to the finish line.