Japan’s most famous activist investor jumped back into the spotlight in 2021, taking on a global private equity giant over one company and scoring a lucrative exit at another.

Yoshiaki Murakami has been locked in a battle with Carlyle Group Inc. over energy and environmental firm Japan Asia Group Ltd., pushing the investing behemoth to double its takeover price and then trumping that offer. Separately, he registered a win at Hoosiers Holdings when the real estate company agreed to buy back his large stake at a higher price than he paid.

Analysts say Murakami may have a controversial past, but his campaigns generate returns for other stock owners. Murakami, a former bureaucrat who quit the trade ministry in 1999 to start his own eponymous fund, was an early champion of shareholder rights in the country before he was convicted for insider trading in 2007. He was sentenced to two years in prison, which was suspended on appeal.