An influential former Sony Corp executive on Monday urged current Chief Executive Kazuo Hirai to focus on innovation than just restructuring in a letter criticising the Japanese firm's management ahead of a shareholder meeting this month. The letter by Tamotsu Iba, a former Sony CFO and vice chairman, was sent to Sony executives the same day that Japan's corporate governance code took effect with the aim of improving shareholder accountability in a country where companies have been criticised for not looking after investors' interests.