Tsuyoshi Maruki stands out like a lone wolf in Japan, where societal intolerance for aggressive shareholder campaigns has spurred a breed of friendly activists.

Not Maruki. Where persuasion does not work, he turns to techniques that include banding with other investors to oust management and filing lawsuits to overhaul corporate practices in order to boost returns for his ¥9.7 billion fund.

"If one always adopts a friendly engagement style, such as having gentle and warm meetings, would the management really change?" said Maruki, 56, who founded Tokyo-based Strategic Capital Inc. in 2012. "After the meeting, it would probably end with a comment like, 'They were nice.' "