Accounting Scandal Threatens Legacy of Billionaire Nidec Founder

Nidec Corp. founder Shigenobu Nagamori once stood alongside his friends SoftBank Group Corp.’s Masayoshi Son and Fast Retailing Co.’s Tadashi Yanai, representing a new breed of Japanese entrepreneurs: Brash, ambitious and scathing in their condemnation of establishment, they called themselves “the three big-talking brothers.” Now, Nidec has flagged a series of suspected cases of improper accounting that risk tarnishing the 81-year-old Nagamori’s legacy and the company he founded, while Son and Yanai’s wealth and global prominence have grown.

Nagamori’s demands on both himself and others helped make Nidec into the world’s largest maker of motors with a ...