Toshiba’s CEO resigned on Wednesday as a buyout offer from a private equity fund stirs turmoil inside the storied Japanese company, with reports suggesting two other funds are considering bids. Nobuaki Kurumatani’s resignation is the latest development in years of upheaval at the firm, which only won back its spot on the first section of the Tokyo stock exchange earlier this year after restructuring. The board accepted Kurumatani’s resignation “as he has completed his mission of revitalising Toshiba”, Osamu Nagayama, head of the firm’s appointment committee told reporters after the company confirmed the departure.