The architect of a revolution at domestic companies is a happy man.

Sipping a drink on the 45th floor of a posh Tokyo hotel last week, Kunio Ito was about to celebrate another milestone, with the nation introducing governance rules for companies that other developed countries have had for years.

The snappily dressed academic headed a 53-person group that spent more than a year reviewing business and financial markets, finally producing recommendations last August that foreshadowed many sweeping changes since, including the code for listed firms that took effect this week.