TOKYO - Effissimo Capital Management, established by ex-colleagues of activist investor Yoshiaki Murakami, has become the top shareholder of two Japanese companies with stakes worth $730 million, filings at Japan’s finance ministry showed on Friday. The Singapore-based investment fund added to its portfolio 8.6 percent of office equipment maker Ricoh Co Ltd and 6.2 percent of shipper Kawasaki Kisen Kaisha Ltd, under a strategy of targeting Japanese firms it deems undervalued. Ricoh and Kawasaki Kisen confirmed the change. Effissimo declined to provide immediate comment. Effissimo is closely watched in Japan because of its passing connection with Murakami, the country’s most famous activist investor. News of its investments is often followed by a rise in the targeted firms’ shares due to expectations for change. Murakami led the so-called Murakami fund until he was convicted of insider trading in 2007. He resurfaced this year, and last month was voted down by shareholders of Kuroda Electric Co over his proposal to change the board of directors. Activist investors are rare in Japan, where the government has lately urged companies to engage more with shareholders and improve corporate governance to attract foreign investors. Earlier this year, industrial robot maker Fanuc Corp said it would to return more cash to shareholders, following pressure from U.S. activist investor Daniel Loeb. Effissimo’s other investments include care provider Nichii Gakkan Co and a majority stake in electronics retailer Yamada Denki Co Ltd. Effissimo is also the second-biggest shareholder of auto parts makers Nissan Shatai Co Ltd and Futaba Industrial Co Ltd.