Four Toshiba Corp directors called on Friday for a shake-up of its management and board, in a sign of revolt after an investigation found the conglomerate colluded with the Japanese government to "beat up" foreign shareholders. The very public push-back by the independent directors, all non-Japanese, is the latest twist in a scandal that shows how the old guard of Japan Inc, while still powerful, can no longer exert full control over shareholders. It comes a day after an explosive, shareholder-commissioned investigation revealed - in startling detail rare for such probes in corporate Japan - how management reached out to the powerful Ministry of Economy, Trade and Industry (METI) to strong-arm activist investors.