But it is the third arrow in that quiver that has Mr Loeb's attention. The Abe government hopes to shed Japan's reputation as a land of strict hierarchy and bureaucracy. Business mistakes were often seen as shameful, and outright confrontation largely disdained.
"There's an entrenched management culture there," said Lawrence B. Lindsey, a former top economist in the administration of George W. Bush. "Activists aren't particularly popular here among management, and they won't be popular in Japan either."
No less than Howard Stringer, Sony's own chairman, has criticized the status quo.
"Japan is a harmonious society which cherishes its social values, including full employment," he said in a speech last year. "That leads to conflicts in a world where shareholder value call for ever greater efficiency."
Yet there have been changes. The percentage of foreign ownership in the Tokyo Stock Exchange's companies nearly quintupled from 1990 to 2008, to 24 percent. And Japanese shareholders have increasingly adopted the aggressive tactics of Western fund managers.
Sony is the biggest bet yet for Mr Loeb, an intense California native who built his name largely upon acidly written letters, berating targets for mismanagement and calling for change.
The strategy has proved profitable. Third Point's returns are up 13.3 percent so far this year and up 2.6 percent for the first week of May. Forbes estimates Mr Loeb's net worth at about $1.5 billion.
Perhaps his most prominent victory has been Third Point's investment in Yahoo, where Mr Loeb pushed for the dismissal of a chief executive after exposing the executive for falsifying academic credentials.
Mindful of Japanese decorum, however, Mr Loeb strikes a more conciliatory tone in his letter to Mr Hirai of Sony. His calls are couched as suggestions aimed at improving the company, rather than aggressive demands.
"Third Point would not have made this substantial investment if we did not believe in a bright future for Sony's global brand, superior technology, and dedicated employees," he wrote. "We are confident that by acting as partners, Sony will grow stronger."
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