SoftBank Corp. chief executive Masayoshi Son anointed the head of the company's U.S.-based Internet investment arm as a future successor, a possible indication of further expansion abroad following the 2013 takeover of U.S. mobile operator Sprint Corp. Mr. Son said he would appoint Nikesh Arora, a former Google executive who has been heading SoftBank's investment arm in San Carlos, Calif., as representative director and president of SoftBank. The head of the firm made the comments after SoftBank announced its latest earning results showing robust profits that beat the company's forecasts for the year ended March 31, despite the continuing struggles to turn around Sprint.