Yoshiaki Murakami, who once struck fear into Japan's boardrooms and split public opinion with bitter activist battles, is now enjoying rare acclaim from executives and being praised as a peacemaker.

Murakami, an outspoken champion of shareholder rights before his conviction for insider trading, has emerged as the key figure in pushing through the merger of refiners Idemitsu Kosan Co. and Showa Shell Sekiyu K.K.

Murakami served as a consultant to Idemitsu's founding family, whose dispute with executives held up the merger, and persuaded them to accept the integration with a series of concessions for shareholders.